Bilingual Education Essay -- Education, Languages, communication, fore

Bilingual facts of life is any school program which utilizes two languages. An example of legal precept in regarding bilingual education is English macrocosm the only language approach that is taught to English language learners in the United States in school districts t altogethery to No Child Left Behind Act of 2001(NCLB). However, historical rationale concerning bilingual education is the history of events that occurred due to bilingual education not being taught in a school district. An example is Meyer V Nebraska (1923). This case briefly was in regards to prohibiting anyone from teaching any subject in any opposite language except for English. Therefore, in this essay three articles will be summarized regarding the legal and historical rationale of bilingual education. Also providing an example of the connection of straight offs educational practice in regards to ELL students in todays classroom environment for each legal and historical event discussed in this essay .In the first article discusses Brown v. Board of Education of Topeka Kansas (Brown v. Board of Education. 1954). The case took place due to a Black female student who had to passport several miles to get to her school through unfavorable conditions that was dangerous for her safety. However, the White school that was in her neighborhood or in walking distance from her cornerstone she was not allowed to attend due to her race. The reason for this historical court case was regarding that state-supported and state mandated laws in the United States favored segregation. Therefore, the Supreme Court ending ruled that all public schools throughout the United States will be desegregated. This means that Black students were able to attend White public schools throughout all of the ... ...n is still occurring regarding bilingual education. Second article explained Lau vs. Nichols court case and what the outcome of this court case confirmed today in bilingual education. Also sugg estions were attached to teachers teaching in todays classroom on how to understand ELL students whose first language is not English. Third article discussed Proposition 227 which was created in San Francisco, atomic number 20 in the year of 1998. This Proposition brought about changes that banned bilingual education to ELL students. Also as a result of this change in Californias constitution banning bilingual education ELL students today lag behind English speaking students. Therefore, these legal and historical rationale in bilingual education discussed in this essay has not resolved the issues of ELL students being successful learners in todays classroom environment.

Fate in Henry James The Beast In The Jungle Essay -- Henry James, The

Henry James always managed to keep certain themes in his works similar. The one that usually stands out most is his literary battles in the midst of Ameri stand and European customs. This is especially app bent in three of his works, Daisy Miller A Study, Roderick Hudson, and The Portrait Of A Lady. However, in his short news report, The Beast In The Jungle, in that respect is a nonher theme that takes center stage. That theme is fate moreover, the failure to control that fate.In The Beast In The Jungle, we are introduced to John Marcher, one of the main characters. instanter afterwards, we meet May Bartram, someone he had met almost ten years prior in Naples, Italy, although he had accidentally thought it to be Rome. The two are getting along splendidly, in a flirtatious way, leaving the reader to wonder most the future of this would-be couple. However, it is then that we find out what ultimately kills the hopes of any kind of romantic connection, as May recalls Johns special holdupYou said you had had from your earliest time, as the deepest thing within you, the sense of being unploughed for something rare and strange, possibly prodigious and terrible, that was sooner or later to happen to you, that you had in your bones the foreboding and the conviction of, and that would perhaps overwhelm you (TBITJ, 338).Marcher believes that he is fated to experience something but he is not sure what it is that he is waiting for. May probes deeper, possibly revealing something about herself and her impulse for a connection, asking, Isnt what you delimit perhaps but the expectation--or at any rate the sense of danger, familiar to so many people--of falling in love? (TBITJ, 339). He talks about a love that he had but that it was not this monumental thing that she talks of. She replies, saying, Then it hasnt been love (TBITJ, 338).This whole conversation has been one flirtatious conclusion of time. However, it quickly turns back to the topic of his fate, cutting sh ort any additional talk of love, possibly leading somewhere. This was a missed opportunity for the both of them because of his fixation with the mysterious destiny. The discussion ends with her promising to watch with him (TBITJ, 340). And yet, the reason that she will see him again is not to pursue any sort of normal relationship. It is simply the desire to be there when whatever happens to him oc... ...life has become and what is should have been. He realizes that the beast was actually the person that he met for the second time back in the abide in Weatherend at the beginning of the story. Henry James works have been known to have a certain autobiographical aspects to them. Looking at his life, one can see that he did not marry either and, just like in Daisy Miller A Study and most of his other works, the main characters story does not end happily. Throughout the entire time of the story, and more-so his life, John Marcher felt that there was something that he should be waitin g for to happen. Something that was spectacular or, instead, brought suffering, he did not have any measure of a clue. Yet he continued to wait for that beast to jump out from the jungle and spark an incident. But what he never understood until the end of the story was that, perhaps, the only beast to be springing forth from the jungle of his life was the pretty swan. Perhaps, the old saying is truly correct, Carpe Diem. engagement CitedJames, Henry. The Beast in the Jungle. The Norton Anthology American Literature. Seventh Edition. Vol. C. New York W. W. Norton & Company, Inc., 2007. 335-376.

Definitions of Words Relating to the Sea :: Ocean Marine Life Aquatics Essays

Definitions of Words Relating to the SeaThe Wave MachineThe wave machine is a simulator that will allow you to create an ocean wave and throttle its height. Most ocean waves are formed when the wind blows across the urines surface. The wave height is determined by three factors wind speed, fetch, and duration.Wind SpeedIn 1805, Sir Francis Beaufort, observing the effects of wind speed upon the sea, devised the Beaufort Wind Scale. Though wind speed is not the only factor in determining wave size, the Beaufort collection plate remains a tool for seafarers to this day. Wind speed is measured in KNOTS. (1 knot is equal to 1.151 mph, or 1.852 kilometers per hour).FetchFetch measures the area of open urine over which wind blows. Like wind duration, the distance waves travel has a significant impact upon their size. Fetch is measured in NAUTICAL MILES. (1 nautical geographical mile is equal to 1.151 miles, or 1.852 kilometers). Wind DurationWind duration reflects how long the wind has blown in the same direction. Even at slower speeds, topographic point winds can create higher and more powerful waves than those resulting from brief, strong gusts.Wave TypesCapillary wavesThe smallest waves created when the wind blows acroos a smooth water surface. Friction between the ancestry and water molecules results in the creation of these small ripples, which are less than .7 inches long.Shallow-Water WavesWind generated waves that travel in water shallower than one-twentieth of their wavelength.Deep-Water WavesWind generated waves that travel in water deeper than one half of their wavelength.SwellA swell is formed when waves move away from the storm or generating area and become more regular. Waves exhibit longish periods and rounded crests, creating a uniform pattern on the ocean surface.Rogue waveA rogue wave is an unusually large wave caused by combining the heights of waves that meet simultaneously.

Masturbation: There is Nothing Wrong With A Little Self -Love Essay

Masturbation is defined as the self-stimulation of the genitals to achieve cozy arousal and pleasure, usually to the point of orgasm/sexual climax (Knowles, 2002). It is a natural process and one of the most common sexual activities that humans learn part in. The subject of masturbation has long been a taboo topic and seen is a sin in many Western religious cultures. Because of this, guilt and attaint are associated with masturbation. In the seventeenth and eighteenth centuries many believed masturbation caused illnesses and it was seen as a disease. This has been proven to be untrue and in fact many health check professionals now believe masturbation to be good for a persons physical and sexual health. Masturbation is a natural healthy process and should not be viewed as something sinful and unnatural. MasturbationMasturbation is one of the first sexual experiences a person will have and it usually done by stimulate the penis or clitoris with a hand, fingers or sex toys ( Knowles, 2002). Masturbation is way of discovering ones sexual potential and is done for various reasons. Some people may masturbate to relieve sexual tension, to help them fall asleep, or as a safe sex alternative just to name a few. It begins as early as infancy and can continue into adulthood with varying frequency, with or with out a partner but is not considered a alternate for sex, merely a variation. Masturbation does not cause any physical injury or harm to the body, and can be performed in moderation throughout a persons lifetime as a part of normal sexual behavior (Knowles, 2002). The HateMasturbation has been viewed as a shameful act having pathological origins and negative physical and mental health consequences(Knowles, 2002). T... ...d Johnson on Sex and Human Loving. Boston, MA Little, Brown and Company.Moglia, Ronald Filiberti, and Jon Knowles, eds. (1997). All About Sex A Family Resource on Sex and Sexuality. New York, NY Three Rivers Press.Mosher, Donald L. , and Susan G. Vonderheide. (1985). Contributions of Sex Guilt and Masturbation Guilt to Womens Contraceptive Attitudes and Use. The Journal of Sex Research, 21(1), 2439.National Survey of Sexual Health and fashion (NSSHB). Findings from the National Survey of Sexual Health and Behavior, Centre for Sexual Health Promotion, Indiana University. Journal of Sexual Medicine, Vol. 7, Supplement 5.Rowan, Edward L. (2000). The Joy of SelfPleasuring. New York, NY Prometheus Books.Yarber, W. L., Sayad, B. J., & Strong, B. (2010). Human sex activity diversity in contemporary America (7th ed.). New York McGraw-Hill Higher Education.

Reparations to Descendants of Slaves Should Have Ceased Long Ago Essay

Reparations to Descendants of Slaves Should Have Ceased Long AgoIn this day and time the world is heavily concerned with political and social disciplinary ness, thus everyone is catered too and no money changes hands. The idea and arguments of paying reparations to the descendants of slaves has been in the American media and courthouses since the English barrister James Grahame published a groundbreaking oblige in 1850 setting the first claim for reparations in the United States. It is no surprise that these allegations arose so soon aft(prenominal) the abolishing of slavery at the culmination of the well-behaved War. Free blacks and enslaved blacks are accredited with building a nation on their backs, that is not so America was built on the backs of the heroic men who served in the American Revolution and the victorious soldiers who reconciled a broken country after the Civil War. Reparations cannot be paid to those whom it is not owed. America has been heavily criticized for p iano supporting slavery in the North and celebrating the institution of slavery in the South. It seems quite puzzling as to why reparations are so sought after by African Americans in the country, when none of them are direct descendants of those who were enslaved. African Americans have been so bold to even bring forth allegations against nations in Europe for starting and profiting from the slave trade as well as the colonization of Africa, it we as a civilized people did our homework we would find that it was capitalistic tribes of Africa who staged the capturing of the slaves thus setting the wheels of slavery in motion. This is the main reason why America can not and will not be charged with the heinous act of paying billions of tax dollars to non-existent sl... ...just settlement of emotional, physical, mental, or financial debt. As John Carroll fervently proclaims I didnt do it My ancestors didnt do it The people who did it are dead now. Slavery is a worldwide epidemic, it has been passed down through time, so Judge Halbert I declare that you vehemently clear America, the West, the nations of easterly Europe, and Christians clear of any wrongdoing in saving the slaves from a life of darkness and sin.WE HAVE PAID OUT DEBTS IN FULL kit and boodle Cited PageBrooks, Raymond L. Paying for Past Sins Taking Sides. 16 June 2002.

Reparations to Descendants of Slaves Should Have Ceased Long Ago Essay

Reparations to Descendants of Slaves Should Have Ceased Long AgoIn this sidereal day and time the world is heavily concerned with political and social corrective ness, thus everyone is catered too and no money changes hands. The idea and arguments of paying reparations to the descendants of slaves has been in the American media and courthouses since the English barrister James Grahame published a groundbreaking book in 1850 setting the first claim for reparations in the United States. It is no strike that these allegations arose so soon after(prenominal) the abolishing of slavery at the culmination of the Civil War. Free blacks and enslaved blacks are accredited with building a nation on their backs, that is non so America was built on the backs of the heroic men who served in the American Revolution and the victorious soldiers who reconciled a broken country after the Civil War. Reparations cannot be paid to those whom it is not owed. America has been heavily criticized for quie tly supporting slavery in the North and celebrating the institution of slavery in the South. It seems quite an puzzling as to why reparations are so sought after by African Americans in the country, when none of them are direct descendants of those who were enslaved. African Americans have been so bold to even bring forth allegations against nations in Europe for starting and profiting from the slave trade as well as the small town of Africa, it we as a civilized people did our homework we would find that it was capitalistic tribes of Africa who staged the capturing of the slaves thus setting the wheels of slavery in motion. This is the main reason why America can not and will not be charged with the heinous act of paying billions of tax dollars to non-existent sl... ...just settlement of emotional, physical, mental, or financial debt. As John Carroll fervently proclaims I didnt do it My ancestors didnt do it The people who did it are dead now. Slavery is a worldwide epidemic, it has been passed down through and through time, so Judge Halbert I declare that you vehemently clear America, the West, the nations of Eastern Europe, and Christians clear of any wrongdoing in saving the slaves from a life of tail and sin.WE HAVE PAID OUT DEBTS IN FULL Works Cited PageBrooks, Raymond L. Paying for Past Sins Taking Sides. 16 June 2002.

Sociology and Material Culture

Haley Schweitzer Sociology 1010 Term Paper Sociology and Oops My Mistake Sociology is defined as, the study of pot doing things together or more specifically, the systematic study of the development, structure, interaction, and joint doings of organized groups of human existences (Merriam Webster Dictionary). This paper will examine the discourse of structure in sociology, the sociology of culture, and the deviance and sanctions in sociology. After discussing these topics, I will enlarge my act of norm breaking and how it ties in with these three argonas of sociology.The structure of sociology can be identified as, the relationship of definite entities or groups to each other, enduring patterns of behavior by participants in a cordial system in relation to each other, and institutionalized norms or cognitive frameworks that structure the actions of actors in the social system. essentially saying inwardly the structure be groups, experimental conditiones, roles, and institut ions. In sociology, a group refers to two or more race who interact on a stem of sha red-faced qualities and experiences. A status refers to a specific position within a group, for example, a manager, employee, or a grandma.Within statuses there are two subgroups, ascribed status and achieved status. An ascribed status is one that is unalterable, such as a grandma. An achieved status is one that is obtainable, such as a manager. A role is an expected behavior within a status. For example, while an employee states the position of that role, the employees guidelines determine what behavior is appropriate for his/her role. This is the same concept for a status and a role. An institution is complex social structures that meet basic human needs.There are five main institutions family, economy, education, politics, and religion. The sociology of culture consists of the beliefs, behaviors, objects, and other characteristics common to the members of a particular group or society. Through culture, lot and groups define themselves, conform to societys shared values, and contribute to society. Thus, culture is constructed from three components which are norms, values, and material culture. Norms are rules within a culture that specify how people should consume themselves every day.Read alsoSociology and Social Integration.For example, one norm that may vary among contrasting cultures is oculesics (eye behavior). Americans, for instance, maintain fairly direct eye contact when conversing with others. Asians, on the other hand, may avert their eyes as a sign of politeness and respect. A cultures values are its ideas about what is good, right, fair, and just. For example, a European that came to where I work said there was a saying in his country that Europeans worked to live, while Americans lived to work. So the values are different in America than they are in Europe.Material culture refers to the physical objects, resources, and spaces that people use to define thei r culture. These include homes, neighborhoods, schools, churches and so forth. All of these physical aspects of a culture help to define its members behaviors and perceptions. For example, engineering is a vital aspect of material culture in the United States today. American students must learn to use computers to survive in college and business, in limit to young adults in the Yanomamo society in the Amazon who must learn to build weapons and hunt to survive.Deviance is any behavior that violates social norms, and is usually of sufficient severeness to warrant disapproval from the majority of society. Deviance can be criminal or non-criminal. Today, Americans consider such activities as alcoholism, excessive gambling, being nude in public places, stealing, lying, refusing to batheto name only a fewas aberrant. Sanctions are socially constructed expressions of approval or disapproval. Sanctions can be positive or negative. A positive sanction rewards someone for following a norm and serves to encourage the continuance of a certain type of behavior.For instance, when parents reward a nipper with money for earning good grades, they are positively sanctioning that childs behavior. A negative sanction is a way of communicating that a society, or some group in that society, does not approve of a particular behavior. For instance, imprisoning a criminal for breaking the law, and taking away a teenagers television privileges for breaking curfew are all negative sanctions. The arena I chose for my norm breaking was my downstairs TV room with group of relay transmitters some of which I wasnt well acquainted with. The statuses consisted of many friends with a few friends of friends.The roles to be played in the group were well mannered and somewhat proper of being at someones house that you dont k instanter very well. The expected roles of my close friends and I were to behave politely and welcoming. Most of my friends are well behaved but also a lot of fun to be a round. I have a very diverse group of friends with all different kinds of beliefs. Now since new people I hadnt met before were coming along I made the room all nice, clean and well organized. I didnt want people to come and see my house for the first time and not want to come back.I bought some different snacks and drinks for everyone to enjoy during the plastic film and hopefully make them feel more comfortable and at home. We all gathered on a typical Friday night to watch a photo at my house. One of my closer friends hasnt had much experience with girls but recently I was able to hook him up with a kind of friend of mine so I invited them along to join us. When he and his girlfriend got to the house me and her started some small talk and she said he was lacking in the first kiss department. I told her he was probably just nervous but that I would get to the bottom of it.I thought about it since I had nevertheless to do the whole norm breaking thing and decided this would be the easiest and most comfortable thing I would be able to do. I baseborn I had my close friends there but I also had some strangers that were most likely still trying to figure all the new people out. When the movie started I sat near the couple and observed both of their movements to decide whether or not to do it. The movie ended, I got up and sour the lights on and just as I predicted there she was sending millions of hints his way that he had to be seeing the whole time but still nothing.Well it was now or never I walked right up to her grabbed her face a planted one on her, I looked at her face bright red and utterly confused then looked at Blake and said, Oh she was hinting at you sorry, my mistake, and I walked out of the awkward, silent room for a minute to get myself together. I walked back to a rather confused room with very weird looks from everyone. There was silence for a couple of minutes then I explained to all of them why I did what I did. This resulted in a lot of laughter and uncontrollable crying. But still some judging looks.My negative sanctions were the strange looks from all the new people I had just met as well as the very embarrassed and angry look from Blake. Also that the new people that had come that had come that night would not return and when I would see them around town I was avoided and looked at as a freak. In conclusion, I was able to examine the sanctions of deviant behavior from a personal standpoint and the effects it may have when people decide to break norms in a situation after development the structure of sociology as well as the rules of deviance and sanctions.

Thermodynamic Analysis and Performance Characteristics

AEROSPACE ENGINEERING SCHOOL OF MECHANICAL ENGINEERING AND DESIGN THE THERMODYNAMIC ANALYSIS AND PERFORMANCE CHARACTRISTICS OF A rooterjet railway locomotive JET ENGINE By J. E, Ibok 2011 Supervisor Dr Lionel Ganippa ABSTRACT This die hard focuses on the act digest of a vis-a-vis spool mixed die hard fan resiny locomotive locomotive rail style locomotive railway locomotive. The main nonsubjective was to check out the causes of development hydrogen, kerosene and essential foul up give the sack on the transactance characteristics such as force out thrust, specific burn down consumption and propulsive ability of the turbo commons engine.another(prenominal) aim of this seduce was to introduce the concept of exergy and thermoeconomics synopsis for twin spool mixed f first fan- spirt engine and doom the pieces that contributes the most to the in talent of the engine. A generic theoretical account was carried out employ attack Turb 11 softwargon to begin reaso nable depth psychology results that were put forward with a real-time JT8D-15A fan-jet engine. The parametric analysis was make for ceaseless protect of atomic reactor f woeful grade of fuel and constant turbine approach temperature for solely cardinal fuels.The result were rightfully obtained for these analysis ends and discussed accordingly. Brunel University Mechanical engineering Academic Session 2010/2011 Name of Student Johnson Essien Ibok SupervisorDr Lionel Ganippa Title The deed Characteristics and Thermodynamics Exergy and Thermoeconomics analysis of a Twin reel intricate melt fan- jet locomotive Operating at 30,000ft at M0 0. using Kerosene, natural particle accelerator and Hydrogen give the sack. Abstract This work focuses on the performance analysis of a twin spool mixed turn tail fanjet engine engine. A generic example was carried out using petrol Turb 11 softw ar to obtain reasonable analysis results that were verified with a real-time JT8D- 15A turbofan engine. The parametric analysis was do for constant value of mass flow dictate of fuel and constant turbine inlet temperature for either trine fuels.The result were rightfully obtained for these analysis cases and discussed accordingly. Objectives The main aim of this work is to conduct the parametric round of golf simulation of a twin spool mixed flow turbofan engine and investigate the performance characteristics of it. Another aim of this work is to taper the accomplishments of using hydrogen, Kerosene and natural turgidness fuel on the boilers suit performance of the twin spool mixed flow turbofan engine.Also, the incur of this work is to introduce the use of the spot law of thermodynamicals analysis known as exergy and thermoeconomics in analysis the twin spool mixed flow turbofan engine Background/Applications This work is applicable in so many managements when it comes to the overall performance optimization and feasibility analysis of a jet engine. This work relates to the aerospace and melodic line industries since the turbofan engine is amongst the vast number of jet engine use in propulsion of rail linecrafts.There is increasing storm in the aviation industry to reduce pollution and depletion of energy resources succession at the kindred time maintaining reasonable investment cost and gritty overall performance. Hence, this reoceanrch was conducted in hopes of coming up with a new solution to this problem. Conclusions The main conclusion drawn from the performance analysis is that hydrogen fuel produced the highest thrust level and the concluding specific fuel consumption betwixt the deuce-ace fuels for a constant mass flow rate of fuel.Kerosene fuel generated thrust level discharge be change magnituded if it is mixed with a small amount of hydrogen. The operate jet velocity ratio remained constant despite the increasing rotate ratio for all deuce-ace fuels at constant mass flow rate of fuel. Using the ex ergetic analysis showed that the blaze chamber and the mixer contributed the most to the in force of the turbofan engine. The amount of exergy transferred into the turbofan engine by hydrogen was depleted in the smallest ratio comp atomic number 18d to natural gunman and kerosene for constant mass flow rate of fuel.The thermoeconomics analysis showed that it is best-loved to use local based cost evaluation to quantity specific thermoeconomics cost of thrust than the planetary method since the value was humiliate. Results The results obtained from the simulation using Gas Turb 11 produced an error range of 0. 25% 8. 5% when verified with the actual examen data of the JT8D-15A turbofan engine. The results obtained for the analysis delineate a reference approach pattern suggest at which the parametric analysis was conducted on. The analysis was done in three cases as shown clearly in the test matrix in skirt 1 below. compendium Parameters being varied Parameters Kept Constan t Performance Characteristics case 1 * shunt ratio * Turbine Inlet temperature * HPC force balance * LPC Pressure proportion * caramel brown Pressure Ratio * Velocity ratio * furnish-Air-ratio * Turbine inlet temperature * Net thrust * limited force out Consumption * Thermal capacity * propelling efficiency case 2 * get out Ratio * deuce-ace different fuelsmH2mCH4mC12H23 * Mass flow rate of fuel * HPC Pressure Ratio * LPC Pressure Ratio * yellowish brown Pressure Ratio Case 3 * break Ratio * Three different fuelsmH2mCH4mC12H23 * Turbine inlet temperature * HPC Pressure Ratio * LPC Pressure Ratio * Fan Pressure Ratio Table 1 The Test matrix of the parametric Analysis. The exergy analysis was done for the parametric analysis of case 2 and case 3 where the exergy remnant rates, exergetic efficiency, exergy improvement potential rate and fuel depletion ratio were calculated. The distribution of these results by dint ofout s perpetuallyally component of the turbofan engi ne was exhibited with bar charts and Grassmann draw. The thermoeconomics analysis was conducted for analysis case 2 using kerosene fuel.The specific thermoeconomics cost of thrust was calculated using global and local based cost evaluation methods. ACKNOWLEDGEMENTS stolon of all, I would standardised to thank my parents for their financial support and encouragement because without them I would not be here and be able to do this work. I am deeply thankful to my supervisor, Dr Lionel Ganippa for believing in me and giving me the opportunity to work with him in this field of study. I am also thankful to him for giving the indispensable guidance and advice and his enthusiasm and innovative ideas inspired me. Finally, I would like to thank Mr Joachim Kurzke for providing me with the necessary software program needed for my dissertation. Table of ContentsAcknowledgements i Contents ii tote up of Notations and Subscripts iv List of Tables vi List of kinds vi Chapter 1 macrocos m1 1. 1. Aims and Objectives2 1. 2. Computational Modeling3 Chapter 2 Jet Engines4 2. 1. Performance characteristics4 2. 1. 1. Thrust4 2. 1. 2. Thermal cleverness5 2. 1. 3. propelling efficiency5 2. 1. 4. Overall efficiency6 2. 1. 5. ad hoc burn Consumption6 2. 2. poop and Propellants For Jet Engines7 Chapter 3 fanjet Jet Engines 8 3. 1. Introduction 8 3. 2. Classification of Turbofan Engines9 3. 3. Major portions of a Turbofan Engine10 3. 3. 1. Diffuser10 3. 3. 2. Fan and Compressor11 3. 3. 3. burning at the stake sleeping room12 3. 3. 4. Turbine13 3. 3. 5. Exhaust bird of night14 3. 4.Thermodynamic Process and Cycle of a Twin Spool Mixed bunk Turbofan Engine15 Chapter 4 Mathematical and Gas turb 11 Modeling of the turbofan Engine18 4. 1. Station Numbering and Assumptions18 4. 2. number berth Cycle Simulation of the Turbofan Engine18 4. 3. Off-design confidential information Cycle Simulation of the Turbofan Engine21 4. 3. 1. Module/Component Matching 22 4. 3. 2. Off- Design Point Component Modeling22 Chapter 5 Methodology, Results and Discussions26 5. 1. General Relationship equations of the Major Parameters27 5. 2. Results and Discussions of Parametric cycle Analysis of Case 129 5. 3. Results and Discussions of Parametric Cycle Analysis of Case 235 5. 4.Results and Discussions of Parametric Cycle Analysis of Case 343 Chapter 6 Exergy and Thermoeconomics Analysis of the Turbofan Engine49 6. 1. Exergy Analysis49 6. 1. 1. Exergy Analysis Modeling 50 6. 1. 2. Exergy and Energy Balance Equations of the Components58 6. 1. 3. General Relationships in Exergetic Analysis of the Turbofan Engine60 6. 1. 4. Results and Discussions61 6. 1. 5. Grassmann Diagram72 6. 2. Thermoeconomics Analysis74 6. 2. 1. Thermoeconomics Analysis mold74 6. 2. 2. Global found personify Evaluation76 6. 2. 3. Local found Cost Evaluation77 6. 2. 4. Results and Discussion of the Thermoeconomics Analysis78 Chapter 7 Conclusions and Future Work80 Reference vermiform process A Ex ergy Analysis Results Appendix B Thermoeconomics Analysis resultsList of Notations and Units ? isentropic efficiency ? Total Pressure ratio m Mass Flow pose (kg/s) f Fuel/Air Ratio M Mach Number Pt Total drag (kPa) Tt Total Temperature (K) NCV Net Calorific Value (MJ/kg) Ht Total Enthalpy (kJ/kg) V Velocity (m/s) ? Bypass Ratio T Static Temperature (K) P Static Pressure (kPa) N true Spool step on it (RPM) Nc change by reversal Spool Speed (RPM) mc Corrected Mass Flow localize (kg/s) R Universal Gas Constant (kJ/kmolK) ?0 Standard Chemical Exergy (kJ/kmol) Ex Exergy respect (MW) xi Mole figure cp Specific Heat at Constant Pressure (kJ/kgK) ? Ratio of Chemical Exergy to NCV ? Exergetic Efficiency Fuel Depletion Ratio W Power Rate of Work done (MW) List of Subscripts LPT Low Pressure Turbine HPT High Pressure Turbine CC Combustion Chamber HPC High Pressure Compressor LPC Low Pressure Compressor d Diffuser noz Nozzle mix Mixer dest Destruction Rate 0, ambFAR Ambient narrow do wnFuel-Air-Ratio CH Chemical PH Physical KN Kinetic PN Potential IP Exergy Improvement Potential Rate (MW) CRF Cost Recovery Factor c Specific Thermoeconomic Cost (MJ/kg) STD Standard Temperature and Pressure dope Turbine Inlet Temperature TSFC Thrust Specific Fuel Consumption (g/kNs) SFC Specific Fuel Consumption p Propulsive TH ThermalO Overall T Thrust equip Equipment PEC Capital Cost of Equipment List of Tables Table 1 input parameters for Design Point Cycle Simulation on Gas Turb 1119 Table 2 Comparison table for the Actual Test Data and fake Data using gas Turb 1121 Table 3 Comparison Table for Actual Test Data and Simulated Off-Design Point data Using gas Turb 11. 25 Table 4 Equivalence Ratio of the three Fuels Combustion Processes 62 Table 5 Assumed Capital costs of Each Component of the Turbofan Engine. 75 Table 6 Flow of Specific Thermoeconomics Cost in all the Components 79 List of conceptions Figure 1 Classification of Turbofan Engine9Figure 2 Layout of Forward Fan Tw in Spool Mixed Flow Turbofan16 Figure 3 T-S Diagram for the Forward Fan Twin Spool Mixed Flow Turbofan17 Figure 4 Design Point Cycle Simulation Algorithm Using Gas Turb 1120 Figure 5 fashion model of a Compressor Performance Map/Curve24 Figure 6 make of Varying Bypass Ratio at Constant Values of TIT on Fuel-Air-Ratio30 Figure 7 Effects of Varying Bypass Ratio at Constant Values of TIT on Exit Velocity Ratio30 Figure 8 Effects of Varying Bypass Ratio at Constant Values of TIT on LPT Exit Pressure Ratio31 Figure 9 Effects of Varying Bypass Ratio at Constant Values of TIT on Net Thrust32 Figure 10 Effects of Varying Bypass Ratio at Constant Values of TIT on Specific Fuel Consumption33 Figure 11 Effects of Varying Bypass Ratio at Constant Values of TIT on Propulsive Efficiency34 Figure 12 Effects of Varying Bypass Ratio t Constant Values of TIT on Thermal Efficiency35 Figure 13 T-S diagram of using Hydrogen Fuel when the bypass Ratio is increased36 Figure 14 division of Fuel-Air-Rati o with Bypass Ratio at Constant Fuel Flow Rate using three different Fuels37 Figure 15 Variation of TIT with Bypass Ratio at Constant Fuel Flow Rate using three different Fuels37 Figure 16 Variation of Exit Velocity Ratio with Bypass Ratio at Constant Fuel Flow Rate using three different Fuels38 Figure 17 Variation of LPT Exit Pressure Ratio with Bypass Ratio at Constant Fuel Flow Rate using three different Fuels39 Figure 18 Variation of Net Thrust with Bypass Ratio at Constant Fuel Flow Rate using three different Fuels40 Figure 19 Variation of Specific Fuel Consumption with Bypass Ratio at Constant Fuel Flow Rate using three different Fuels41 Figure 20 Variation of Thermal Efficiency with Bypass Ratio at Constant Fuel Flow Rate using three different Fuels42 Figure 21 Variation of Propulsive Efficiency with Bypass Ratio at Constant Fuel Flow Rate using three different Fuels43 Figure 22 Variation of Fuel-Air-Ratio with Bypass Ratio at Constant TIT using the three varied Fuels44 Figu re 23 Variation of Exit Velocity Ratio with Bypass Ratio at Constant TIT using the three Different Fuels44 Figure 24 Variation of LPT Exit Pressure Ratio with Bypass Ratio at Constant TIT using the three Different Fuels45 Figure 25 Variation of Net Thrust with Bypass Ratio at Constant TIT using the three Different Fuels46 Figure 26 Variation of Specific Fuel Consumption with Bypass Ratio at Constant TIT using the three Different Fuels46 Figure 27 Variation of Propulsive Efficiency with Bypass Ratio at Constant TIT using the three Different Fuels47 Figure 28 Variation of Thermal Efficiency with Bypass Ratio at Constant TIT using the three Different Fuels48 Figure 29 Variation of Exergy Destruction Rate Using the three Fuels for Analysis Case 262 Figure 30 Variation of Exergy Destruction Rate Using the three Fuels for Analysis Case 364 Figure 31 Variation of Exergetic Efficiencies Using the three Fuels for Analysis Case 266 Figure 32 Variation of Exergetic Efficiencies Using the three Fuels for Analysis Case 367 Figure 33 Distribution of Exergy Improvement potential Rate Using the three Fuels for Analysis Case 268 Figure 34 Distribution of Exergy Improvement potential Rate Using the three Fuels for Analysis Case 369 Figure 35 variation of Fuel Depletion ratio using the Three Fuels for Analysis Case 270 Figure 36 variation of Fuel Depletion ratio using the Three Fuels for Analysis Case 371 Figure 37 Grassmann Diagram for the Exergetic analysis of Case 2 using kerosene Fuel for the Turbofan engine. 72 Chapter 1 Introduction Jet engines are complex thermodynamic placements that use a series of non-linear equation to define their thermodynamic processes and they operate under the principle of Brayton cycle.Brayton cycle is a cycle that comprises of the compressor, combustor and turbine working as a unit. Additionally, the study parameters that dictate the operational check intos of the engine at any institutionalise during the process are the congeneric elevat ion and Mach number. Mach number is the ratio of the velocity of the jet engine to the speed of sound. Basically, the main settle of this type of thermodynamic musical arrangement in aerospace industry is to accelerate a jet of radiate and as a result, generate enough thrust needed for flight. In addition, the design of jet engines is dependent of what purpose it impart be used for in golf-club to derive its maximum performance.For instance, in military application, jet engines are required to generate maximum thrust in lower limit response time which consumes a lot of fuel whereas commercial jet engines are required to less noise generative, less fuel overwhelming and at the same time realize high overall efficiency (El-sayed, 2008). There are certain factors that jet engine manufacturers take into condition when designing jet engines which are the direct cost, engine noise, environmental emissions, fuel burn and overall efficiency. Accordingly, this has caused a global ma rket competition for engine manufacturers like Rolls Royce, Pratt and Whitney, General voltaic and CFM on who can produce the most efficient jet engines.In fact, Pratt and Whitney Company is working on a geared turbofan jet engine that they mean pull up stakes reduce fuel burn, produce lesser noise and emit less toxics while General Electric is coming up with simpler ecore jet engines that result be more fuel efficient than the current jet engines with as much as nearly cardinal fifths of current jet engines (Cassidy, 2008). Taking all that has been said into consideration, it can easily be asserted that by reducing the fuel consumption of the jet engine, the total temperature at the turbine blades entrust reduce thereby increasing the operating life and overall efficiency of the engine. Also, the total cost of the engine can be cut down. Indeed, Dr Pallan cited in (Ward, 2007) verbalize that reducing the fuel consumption by as small-minded as 1% is highly longed after by engine manufacturers and this can result in very world-shaking increase in the overall performance.In a general block of view, it can be said that the maximum presage of achievement for jet engine manufacturers would be to design an engine that consumes the minimum amount of work in the compressor unit while generating the maximum amount of work in the turbine unit at minimum fuel supply. The main purpose of this work is to analyse the thermodynamic processes and performance of a jet engine using a simulation tool, exergy and thermoeconomics concept. 1. 1. Aims and Objectives The main objective of this work is to carry out the thermodynamic analysis and show the performance characteristics of a turbofan jet engine. In this work, the vivid exposition of the thermodynamics processes and cycle of each component of the turbofan engine starting from the distributed to the honker will be covered. Also, the first and second law of thermodynamics with other laws will be employ extens ively throughout this work.However, in the aspect of performance characteristics of the turbofan engine, a generic simulation will be carried out on a twin spool mixed flow turbofan engine. To relate this work to real life application, a JT8D-15A turbofan engine manufactured by Pratt and Whitney Company will be used as the twin spool mixed flow turbofan for the simulation using the original design data. Indeed, the simulation tool that will be used is GasTurb 11 which was designed by Joachim Kurke and for more details on how it works can be found in (Kurke, 2007). This work will use the reference design rank of the twin spool mixed flow turbofan at sea level with maximum take-off thrust to obtain the operating point of 30,000ft at M0 0. using the off-design performance simulation which will serve as the operating design point for the analysis in this work since the engine will spend most of its time in the cruise phase between 30000ft to 38000ft. The purpose of carrying this generi c simulation of the turbofan engine is to investigate the effects of variable bypass ratio and turbine inlet temperature (thermic limit parameter) on the performance characteristics of the turbofan engine. In other words, the parametric cycle studies of the turbofan engine. This investigation will be done for three different cases which case 1 will be studying the effects of varying bypass ratio and turbine inlet temperature on the performance characteristics of the turbofan engine when some of the design choices are kept constant.The second case of study will be the comparison of the performance characteristics of the turbofan engine when three different fuels (kerosene, natural gas and Hydrogen) are used at the same mass flow rate using the same design point in case 1. Finally, the third case of study will be the comparison of the performance characteristics of the turbofan engine when the three fuels are undergoing the same combustion process that is constant turbine inlet tempe rature for the design point in case 1. This aspect of this analysis is very important owing to the maturation problem of greenhouse effect and depletion of energy resources. In fact, statistics by the intergovernmental panel shows that aerospace industry is amongst one of the fast growing sources of greenhouse effect and that the emission of deoxycytidine monophosphate dioxide will increase to five times what it is presently which is 3% (Symonds, 2005).Based on this, using resource fuels like hydrogen and natural gas can incline to reduce pollution and consumption of energy resources risk and this work aims to show how that can be achieved while the overall efficiency of the engine is still high. Another approach of analysis in this work will be the use of the second law of thermodynamics analysis also known as exergy and thermoeconomics. This aspect of analysis of the turbofan engine will be done for the parametric analysis of case 2 and case 3 in efforts to also compare the th ree fuels that are being considered and show which fuel will cause the turbofan engine components to be most inefficient or have the most irreversibility.This analysis will be done by calculating the exergy relationships such as exergy transfer rates, exergy destruction rates, exergetic efficiencies, exergy improvement potential rates, and fuel depletion ratios. Furthermore, the exergy analysis will be represented in a Grassmann diagram for parametric analysis case 2 of study. However, as for the thermoeconomics analysis of the turbofan engine, only parametric analysis case 3 studies will be done for only kerosene fuel and this work will aim to show how to use concept of local and global evaluation of thermoeconomic cost. 1. 2. Computational Modelling It will be very expensive and time wasting to design and develop new aircraft engine whenever an optimization or analysis wants to be done.In fact, Caoa Y, Jin, Meng and Fletcher (2005) stated that new ways should be developed to reduc e aircraft engine design, maintenance and manufacturing cost in order to have in effect(p) worldwide market competition. Surprisingly, computer modelling is one approach of reducing manufacturing cost and time wasting. Computational modelling can simply be defined as the use of computer codes to replicate a typical form using some of its original data in order to analyse the system at varying conditions. The other side of the medallion shows simulation. There are many types of simulation tools normally used in simulating gas turbines such as Matlab/simulink, Modelica, Gas Turb 11, NPSS and many more. However, the simulation tool that will be adopted for the purpose of this dissertation is Gas Turb 11 designed by Joachim Kurzke.Gas Turb 11 is a language oriented program with a command prompt that calculates the output data without using block diagrams or graphical interface. It is user friendly in a understanding that it is easy to find the tools library and to substitute data in for simulation. The Gas Turb 11 is specifically designed for simulation of all kinds of gas turbines starting from ply generators to jet engines. Gas Turb 11 usually carries out two types of analysis which are the on design cycle point simulation and off-design cycle point simulation. Engine design point cycle simulation involves the study of comparing gas turbines of different geometry. This cycle design point essential be defined before any other simulation can be done.On the other hand, off-design performance cycle point simulation involves the study of the doings of a gas turbine with known geometry. This cycle outlines the performance characteristics of each component such as performance maps, Overall efficiency. The type of simulation that will be done in this dissertation will involve the off-design and design point cycle. Chapter 2 Jet Engines 2. 1. Performance Parameter of Jet Engines 2. 2. 1. Thrust Thrust is the way of quantifying the ability of a jet engine to effecti vely utilise the energy added to it in order to propel or push itself forward in the smuggled eye attention of the pulling jet in the exhaust nozzle.In other words, it is the reactive force to the force imparted by the exiting jet in the nozzle in accordance to Isaac norths third law of motion. It is the most important parameter that has to be obtained for any jet engine and it depends heavily on the ingested mass of air, exiting velocity and constrict sensation, the welkin of the nozzle, the flight velocity and close conditions. In fact, the mathematical expression for thrust which incorporates these factors is shown below as. Thrust=meVe-m0V0+Pe-P0Ae Where, e=the exit conditions at the exhaust nozzle, 0=ambient conditions at the inlet me=m0+mfuel Momentum Thrust=meVe This is the thrust obtained from the reaction of the hot exhaust gases high velocity.Momentum Drag= m0V0 This the friction or drag force caused by the high velocity ingestion of air mass at the inlet. Pressu re Thrust=Pe-P0Ae This force is generated as a result of the high exit nonoperational printing press compared to the ambient jam which pushes back at the engine. Gross Thrust=meVe+Pe-P0Ae It is the maximum obtainable positive thrust a jet engine can have when the drag forces are ignored. Special Cases of Thrust Take-off Thrust It is the thrust a jet engine can generate with its own power at quiet or low power setting which means the nervous impulse drag component of thrust is ignored and the power of the engine at this point is equivalent to zero.This can be used to explain why the thrust of an engine at take-off condition is usually higher than at cruise condition since there is no momentum drag and effects of varying ambient condition. This only applies to turbojet, turbofan, and turboprop jet engines but when it comes to ramjet and scramjet, the air flow has to be accelerated by a booster system before it can start producing a positive take-off thrust. Pressure Thrust Compo nent This is the thrust generated as a result of the static atmospheric pressures of the exiting jet and ambient environment. In ideal cases where the nozzle has perfectly expanded the jet exit pressure to that of the ambient condition, the pressure thrust component will disappear which this case is not possible in reality.However, if the nozzle is choked which indicates that the ambient pressure is lower than the exit pressure of the jet, the pressure thrust component will have a positive effect on the net thrust. Also, if the nozzle tends to over expand the jet because of low energy addition to the jet and the exit pressure is lower than the ambient pressure, the pressure thrust component will have a negative effect on net thrust. 2. 2. 2. Thermal efficiency It is simply the measure at which energy in the engine system is born-again. In other words, it is the measure at which total energy supplied to the engine system as waken transfer is converted to energizing energy.In anoth er way, it can easily be said to be the ratio of the power generated in the engine airflow to the rate at which energy is supplied in the fuel. ?TH=Power Generated in the Engine AirflowRate of Energy Supplied in the Fuel =12? meVe2-12? m0V02mfuel? NCV 2. 2. 3. Propulsive efficiency It is a measure at which kinetic energy possessed by air as it passes through the engine is converted into power of the propulsion of the engine. In mathematical terms, it is simply known as the ratio of thrust power to the power generated in the engine airflow. ?p=Thrust PowerPower Generated in the Engine Airflow = T? V012? meVe2-12? m0V02 2. 2. 4. Overall EfficiencyAs the name overall depicts, it is the resultant efficiency of a jet engine can have which is simply the product of the thermal and propulsive efficiencies. In mathematical terms, it is represented as shown below. ?O=? TH p =12? meVe2-12? m0V02mfuel? NCV? T? V012? meVe2-12? m0V02 =T? V0mfuel? NCV 2. 2. 5. Specific Fuel Consumption Specific fu el consumption as any other performance characteristics is a ratio and surprisingly it has a major effect on the economics of the aircraft as it is used to determine the aircrafts flight ticket costs. Specific fuel consumption has different expressions depending on what type of jet engine it is. For instance, in ramjet, turbojet and turbofan jet engines, it is the measure of the fuel mass flow rate to the thrust force generated.Also, it is sometimes called the thrust specific fuel consumption (TSFC). TSFC=mfT However, in turbopropeller jet engines, it is the ratio of the fuel mass flow rate to the power generated in the engine shaft by the turbomachinery. It is sometimes referred to as the brake-specific fuel consumption (BSFC). TFSC=mfSP 2. 2. Fuel and Propellants for Jet Engines Fuels can implicitly be defined as substances used to add conflagrate energy to a system through combustion or other processes. Fuels are mostly hydrocarbons like kerosene, diesel, petrol, alcohol, paraf fin and butane and can also be in the form of individually alleviate reactive molecular substances like hydrogen or chemical composites like natural gas, coal, wood.The gaseous state substances used as fuels such as hydrogen, and natural gas (94% methane and 6% ethane) are usually made into a cryogenic state as in liquefied at very low temperature because of their low boiling point. It can easily be asserted by anyone that the only purpose that fuels have in jet engines is to add energy but little do they know that the purposes grows as the speed of the aircraft increases. For instance, Kerrebrock (2002) stated that supersonic aircrafts which attains very high stagnation temperature that can clear destabilization to the airframe structure, engine component and primitive substances like lubricants, uses its fuel as a coolant to this parts or components.The energy added by the fuel burned per unit mass of air flow is called the change value of the fuel and it is a very crucial par ameter to be defined before any combustion process analysis is done on a jet engine since it shows how complete the combustion process is through efficiency. The heating value can either be said to be higher or lower depending on if the water product of combustion is a vapour or a liquid. Since the combustion process in jet engine produces vaporised water, the lower heating value of the fuel is used. The most frequently used fuels for jet engines are kerosene jet A1, A2, JP10 and many more but diesel can also be used. The disadvantages of these fuels are their inevitable emission of toxic substances that contribute to greenhouse effect and their risk of depletion.Accordingly, this has been the driving force for the use of alternative fuels such as cryogenic hydrogen and natural gas which is believed will reduce toxic emissions. Besides, hydrogen is a carbon-free energy carrier and possesses almost no risk of toxic emission since most of its combustion product will be water Chiesa an d Laozza (2005). Chapter 3 Turbofan Jet Engine 3. 1. Introduction surrounded by 1936 and the next decade when turbofan engines were invented, people showed little or no interest in them as they described them to be a complicated variance of a turbojet engine. However, in 1956, the benefits of turbofan engines started to be noticed as major companies like Rolls-Royce and General Electric began manufacturing them.Since then, it is been one of the most used jet engine for commercial purposes because of its low fuel consumption and less noise production. In fact, it has been concluded to be the most legitimate jet engine ever manufactured El Sayed (2008). The turbofan jet engine gas generator unit comprises of a fan unit, compressor section, combustion chamber and turbine unit. Fundamentally, a turbofan jet engine operates as a result of the compressors pressuring air and supplying it afterwards for further processing. The majority of the pressurised air is bypassed around the core o f the engine through a duct to be mixed or exhausted whereas the rest of it flows into the main engine core where it combusts with the fuel in the combustion chamber.The hot expanded gas products from the combustion process passes through the turbine thereby rotating the turbine as it leaves the engine. Consequently, the rotating turbine spins the engine spool which in turn rotates the other turbo machinery in the engine. This causes the front fan to pressurise more and more air into the engine for the process to start all over again in continuous state. The turbofan engine is believed to be the perfect confederacy of the turboprop and turbojet engine and as a result, its advantages are usually compared to that of the turboprop and turbojet. In fact, Kerrebrock (1992) said that turbofan engine provides a better way of improving the propulsive efficiency of a basic turbojet.It is asserted that at low power setting, low altitude condition and low speed, the turbofan engine is more fu el efficient and has better performance than a turbojet engine. Unlike turboprop engine where vibration occurs in the propeller blades at relative low velocities, the fan in the turbofan engine can attain high relative velocities of Mach 0. 9 before vibration occurs. Also, since the fan in turbofan engines has many blades, it is more stable than the single propeller so even if the vibration velocity is reached, the vibration will not destabilize the airflow because the vibrations are almost negligible. Since the flow into the diffuser of the turbofan is usually subsonic, there very slim chances of shock waves being developed at the entrance. 3. 2. Classification of Turbofan EnginesThere are mixed types of turbofan engine ranging from high and low bypass ratio, afterburning and non-afterburning, mixed and unmixed flow with multi-spool, after fan and geared or ungeared. The classification of the various types of turbofan engines is shown below in figure 1. Nonetheless, the type of tur bofan engine that would be used for the purpose of this dissertation is a forward fan two spool mixed flow turbofan engine. This type of turbofan engine was chosen because it is the compromise of a simple and complex turbofan engine. This is said because it comprises of almost all the classes of a turbofan which are low bypass ratio, forward fan with mixed flow, twin spool with ungeared fan.Moreover, because of the mixed flow introduced, it produces supernumerary thrust in the hot nozzle compared to the high bypass and it can also permit the addition of afterburner which produces a lot of thrust while consuming a lot of fuel which makes it suitable for military application which shows little worry on fuel consumption. In essence, carrying out a study on this type of turbofan engine will be of great relevance to the military air force sector especially if new research is discovered. TURBOFAN ENGINES Low Bypass Ratio Aft Fan Forward Fan Nonafterburning Afterburning High Bypass Ratio Geared Fan Single Spool unforesightful Duct Ungeared Fan Two Spool Mixed Fan and Core Flow Unmixed Flow Long Duct Three SpoolFigure 1 Classification of Turbofan Jet Engines (El-sayed, 2008) 3. 3. Major Components of Turbofan Engine 3. 4. 1. Diffuser or Inlet Diffuser is the first component that air encounters as it flows into the engine. Basically, the purpose of a diffuser is to suck in air smoothly into the engine, reduce the velocity of the air, increase the static pressure of the air and finally, supply the air in a uniform flow to the compressor. Given the fact that overall performance of an engine is highly dependent on the pressure supplied to the burner, it is necessary to design a diffuser that incurs the minimum amount of pressure termination.To demonstrate this, Flack (2005) stated that if the diffuser incurs a large total pressure red ink, the total pressure in the burner will be reduced by the compressor total pressure ratio time this loss. In other words, a small p ressure drop in the diffuser can translate into a real drop in the total pressure supplied to the burner. Another point taken into consideration when designing a diffuser is the angle because if the angle is too big, there will be tendency of eddy flow generation due to early separation. The major causes of pressure losses in the diffuser are as follows. First, losses due to generation of shock waves outside the diffuser and it majorly occur in supersonic diffusers.Secondly, the loss due to the unfavourable or adverse pressure gradient of the diffuser geometry which makes the flow separate a lot earlier and generates eddies. This separation causes a oblique area which makes the velocity not to be reduced by much. Due to the separation, the wall shear deteriorates the static pressure even further. Further analysis done by El-Sayed (2008), describes ways of accounting for this losses like using Fanno line flow and combined area and friction. Thermodynamic Process Equation In this an alysis, the loss due to heat transfer is negligible so the process can be adiabatic. The initial kinetic energy is used to raise the static pressure p0 to the total pressure ? =pt2pt0 (inlet pressure recovery) efficiency ? d=IdealReal=ht2s-h0ht2-h0 assuming the gas is ideal and the specific heat at constant pressure is constant efficiency ? d=Tt2s-T0Tt2-T0 simplifying the equation given that ht0=ht2=ht2s and Tt2=Tt0and pt2s=pt2 TtT0=1+? -12M02 and TtT0=ptp0? -1? pt2p0=1+ ? d? -12M02 -1 3. 4. 2. Fan And Compressors Compressor is a very crucial component for the operation of an engine in the sense that it prepares the air for the combustion process in the burner. The main purpose of a compressor as the first rotating component is to use its rotating blades to add kinetic energy to the air and later translate it into total pressure increase.There are basically two types of compressors which are the centrifugal and the axile compressor. Firstly, centrifugal compressor as the name implie s changes the focalisation of an axial airflow to a radial outflow of the air. It was the early compressors adapted in jet engines. It comprises of three main parts which are the impellers, the diffusers and the compressor manifold. The purpose of the impeller is to change the direction of the flow from axial to radial and at the same time increases its static pressure. The diffuser slows down the airflow and further increase the static pressure as it is supplied axially by the compressor manifold to the combustion chamber.The centrifugal compressor is advantageous because the cost of manufacturing it is low compared to axial compressor and as a result is suitable for small engines like turboshafts and turboprops. It is also advantageous because the pressure ratios at single stage are higher than that of the axial compressor. The centrifugal compressor has the tendency of attaining low flow rates and as a result is ideally suitable for helicopters and small aircrafts which require low flow rates. On the other hand, the centrifugal compressor cannot attain high pressure ratio and so it is not suitable when high peak efficiency is required. It incurs a lot of losses due to the change in direction. Secondly, an axial compressor is the most reliable type of compressor and is usually applied when higher pressure ratios of up to 401 are required.An axial compressor does not change the axial flow direction of the air but increases the total pressure. Indeed, an axial compressor comprises of three major components which are the rotor with blades, stator can and the inlet guide vane. A stage is a combination of a stator and a rotor. The assembly of the full rotor blade and stator can form the number of stages in a compressor and the greater the number of stages, the higher the total pressure ratio. In this arrangement, the air flows into the inlet guide vane and then into the rotor and stator assembly where compression starts. Also, the space of the rotor and stator reduces along the whole unit which signifies a reduction in volume which induces the increase in pressure.A fan or low pressure compressor is a type of axial compressor but the only differences are that the blades are longer, the total pressure ratio is lower than the typical compressor and the number of stages is usually 1 or 2. The main purpose of creating a fan is to compress more air and to create a bypass air which can be used to generate addition thrust or used for mixing process. Fan Equation Process Given that, isentropic efficiency ? fan= Ideal CycleActual cycle=ht3s-ht2ht3-ht2 Since the specific heat is constant, the equation deduces to ? fan=Tt3s-Tt2Tt3-Tt2 Simplifying the equation whenpt3s=pt3, Tt3sTt2=pt3pt2? -1? , ? fan=pt3pt2 and ? fan=Tt3Tt2 ? fan=? fan? -1? -1? fan-1 Bypass Ratio=msma where ms is the bypass flow rate and ma is the engine core flow rate.For the high pressure compressor, the equations remain the same as that of the fan except the changes in station nu mbering and the bypass ratio. 3. 4. 3. Combustion Chamber/ Burner The combustion chamber as the Brayton cycle implies is the only source of heat energy addition to the system. Accordingly, the combustion chamber causes very significant increase in the temperature of the air which results in the air gaining enormous internal energy. This energy gained is extracted to be used to power the turbine while the rest is used to create highly accelerated gases from the nozzle. There are three types of combustor namely the can combustor, the annular combustor and the cannular combustor.The main considerations when designing a combustion chamber is to verify that the combustion process is complete with no fuel waste, the combustor should have long life materials because any failure can lead to engine explosion. The other consideration is that the air must be heated enough above the ignition fuel temperature in order to ensure stoichiometric combustion. Equations of the Combustion Chamber In t he real process of the combustor, total and static pressure drops and the temperature also drop. The major causes of pressure losses are the high level of irreversibility or non-isentropic process and gluey effects in the burner. The burner pressure ratio ? =pt5pt4Burner temperature ratio ? b=Tt5Tt4 Since no work is done only heat transfer, the efficiency of the burner is analysed using the heating value NCV of the fuel used. Thus, efficiency ? b=heat addedHeating value of fuel=ma+mfht5-maht4NCVmf Given that f=mfma, ? b= 1+fht5- ht4NCVf Equivalence Ratio of combustion It is the ratio of the actual fuel to air ratio of the combustion process to the stoichiometric fuel to air ratio. This ratio produces a means of classifying the combustion process to show whether it is a lean, rich or stoichiometric combustion. The mathematical expression for this is as shown below ? =Actual FARStiochiometric FAR 1 Rich combustion process 3. 4. 4. Turbine Turbine can simply be said to be the antonym of a compressor. In response, a turbine extracts molecular kinetic energy from the air and uses it to drive the turbo machineries which results in the pressure and temperature of the air to drop. If truth be told, Flack (2005) asserted that the turbine uses 70% to 80% of the total energy gained by the air in the combustion chamber to drive the turbo machineries while the remaining 20% to 30% is used to generate thrust in the nozzle.Since the geometry of a turbine have favourable pressure gradient unlike the compressor which is adverse, the efficiency of the turbine is usually very high. Since the turbine is the opposite of the compressor, it has exactly the same configuration of rotor and stator but the volume increase across it which induces the pressure drop. One major problem faced when design a turbine is the deterioration of the blades due to high inlet temperature from the combustion chamber. Based on this, (Song et al. 2002) demonstrated that General Electric uses astir(pred icate) 16. 8% of the compressor air to cool the turbine blades of GE 7f engine. Turbine Equation Analysis Given that, Turbine efficiency ? T=ActualIdeal=ht6-ht5ht6s-ht5 T=Tt6-Tt5Tt6s-Tt5 Simplifying the equation given that pt6s=pt6 Tt6sTt5=pt6pt5? -1? ?T=pt6pt5 ? T=Tt6Tt5 ?T=? T-1? T? -1? -1 3. 4. 5. Exhaust Nozzle The nozzle is the final component of the jet engine that the air passes through. The main purposes of the nozzle is to add extra acceleration to the high velocity exiting air, reduces its total pressure to that of ambient condition and finally generate sufficient thrust. There are two conditions that occur in the exit of the nozzle depending on the ambient pressure. The first condition is termed under-expansion which occurs when the ambient pressure is less than the exit pressure of the gases.The result of this is that the exit velocity will be lower than it normally is and this makes the momentum component of thrust to be lower than ideal. On the other hand, it will crea te a positive thrust component for the pressure terms. The second case termed as overexpansion which occurs when the ambient pressure is greater than the exit pressure of the gases. Consequentially, the opposite of what happens in the under-expansion condition occurs where the pressure term is lower and the momentum is higher. Nozzle efficiency ? n=ActualIdeal=ht8-h9ht8-h9s=Tt8-T9Tt8-T9s for constant specific heat Using the steady state energy equation and balancing it out, U9=2ht8-h9 . When specific heat is constant U9=2cpTt8-T9 p9pt8=T9sTt8? -1? T9Tt8=11+? -12M92 p9pt8=11+? -12M92-1+ ? n ? n 3. 4.Thermodynamic Process and Cycle of Twin Spool Mixed Flow Turbofan Engine Before any explanation is done from Figure 2, the blue arrows represent the incoming air into the diffuser and the red represent the air flow into the core of the engine while the black arrow represent the bypass air flow through the fan. Finally, the brown arrow represents the air flow after the bypass air and the c ore air flow have mixed. Based on the arrangement of the turbofan engine in figure 2, it can be seen that air at ambient condition is sucked into the diffuser where the air velocity is reduced and some of its kinetic energy is used to increase the static pressure to the total pressure. The air exiting the diffuser enters the fan or low pressure compressor where it is compressed. Indeed, the molecules of the air gains kinetic and internal energy by colliding rapidly with one another and as a result increase the heat content and static pressure.Also, in the fan, some of the compressed air is bypassed through a duct to be used for the mixing process later while the rest of the air enters into the high pressure compressor of the engine core. In the high pressure compressor, the air is further compressed where the enthalpy and pressure increases as it is released into the combustion chamber. Also, in the high pressure compressor, some of the air mass flow rate is bled out to be used to cool the turbine blades and for air conditioning in the aircraft. In the combustion chamber, the incoming fuel reacts with the air in an oxidation process at constant pressure where the by-product gases gain molecular kinetic energy thereby increasing the enthalpy.This high temperature gases escapes into the high pressure turbine where it is expanded and the gases lose some of their kinetic molecular energy as it enthalpy and static pressure reduces. In other words, it can be said that the molecular kinetic energy of the gases is being converted to mechanical work which is used to power the high pressure spool. Consequently, the gases enters into the low pressure turbine where it is further expanded to a lower pressure and enthalpy as their molecular kinetic energy is converted to mechanical work to power the low pressure spool. These gases escaping from the low pressure turbine enters the mixing zone or mixer after it has lost most of its total enthalpy and mixes with the bypassed cold air from the duct to further reduce its enthalpy as that of the cold air increases.In other words, the cold air absorbs some of the heat energy from the hot gases until they both attain equilibrium enthalpy. The mixture of the cold air and hot gases both escape at the same equilibrium enthalpy and pressure through the nozzle where their velocity is increased and the pressure is reduced considerably to that of the ambient condition. Furthermore, the exhausted high velocity gases is used to produced thrust for propulsion according to Newtons third law of motion (In every action, there is equal and opposite reaction). 2 4. 5 6 4 13 0 HPC diffuse FAN/LPC HPT LPT NOZZLE COMBUSTION CHAMBER 2. 5 3 5 8 16 BYPASS DUCT HP Spool LP Spool MIXING ZONEFigure 2 Layout of a Forward Fan Twin Spool Mixed Flow Turbofan Engine P0 P3 P4. 5 P5 P8 P6 P2. 5 P2 P13 P4 sulfur (S)(kJ/kg) TEMPERATURE (K) Figure 3 T-S Diagrams for the Forward Fan Twin Spool Mixed Flow Turbofan Engine Chapter 4 Mathematic al and Gas Turb 11 Modelling of the Engine 4. 1. Station Numbering and Assumptions Station numbering is a very crucial step that has to be taken when analysis of any thermodynamic system involving many processes is to be done. Moreover, station numbering contributes immensely to showing how the properties of one process relate to another and how the interaction between these processes derives the functional relationship of the thermodynamic system.Returning to the work in hand, the station numbering system that has been adopted for this work on a JT8D-15A turbofan engine is in accordance with the Aerospace Recommended Practice (ARP) and it is shown in figure 2. Assumptions The following assumption were made based on Mattingly (2002) and Kurzke (2007) in order to perform the modelling as listed below * The air flow through the engine is assumed to be steady and one dimensional * The fan and the low pressure Compressor are driven by the low pressure turbine * The overall engine is ass umed to have no bleeds in mass flow or power off-take in turbine. * The nozzle of the engine is choked which means the exit pressure will be greater than the ambient pressure. The air is assumed to act as a half ideal gas where the specific heat and ratio is dependent on temperature only. * The areas of each station of the engine is assumed to be constant 4. 2. Design Point Cycle Analysis of the Turbofan Engine The off-design or performance cycle analysis cannot be done without the design point cycle being defined. The design point cycle in this analysis is obtained using exactly the same data used in the actual test analysis for a JT8D-15A turbofan engine operating at sea level with maximum take-off thrust as shown in (JT8D Typical Temperature and Pressure) and (ICAO). Some of the input parameters such as the isentropic efficiencies and pressure ratios from the actual test data had to be calculated.Since not all the input parameters were given from the actual test data, some of the parameters like inlet change by reversal mass flow rate, diffuser pressure ratio and efficiency mechanical spool efficiency had to be guessed in order to complete the analysis and the data are represented below in Table 1. With all the Input Parameter being specified as shown in table 1, the design point cycle simulation of the JT8D-15A turbofan Engine using the Gas Turb 11 software can then be performed. All the steps taken to model the mixed flow turbofan engine on Gas Turb 11 is clearly represented in the algorithm shown in figure 3 below. COMPONENT INPUT PARAMETER DIFFUSER Pressure Ratio (? d) 1 Inlet Corrected Mass Flow Rate (mc2) 138. 618 kg/s FAN Pressure Ratio (? fan) 2. 054 Isentropic Efficiency (? fan) 0. 78 Bypass Ratio (? ) 1. 08 Low Pressure Compressor (LPC) Pressure Ratio (? LPC) 4. 7 Isentropic Efficiency (? LPC) 0. 88 Nominal Low Pressure guesswork Speed (NLP) 8160RPM High Pressure Compressor (HPC) Pressure Ratio (? HPC) 3. 77 Isentropic Efficiency (? HPC) 0. 864 Nominal Low Pressure Shaft Speed (NHP) 11420RPM Combustion Chamber (cc) Pressure Ratio (? CC) 0. 934 Isentropic Efficiency (? CC) 0. 99 Burner Exit Temperature (TIT) 1277. 15K High Pressure Turbine (HPT) Isentropic Efficiency (? HPT) 0. 9 HP Spool Mechanical efficiency (? m) 1 Low Pressure Turbine (LPT) Isentropic Efficiency (? LPT) 0. 91 LP Spool Mechanical efficiency (? m) 1 Table 1 Input Parameters for the Design Point Cycle Simulation STARTSpecify all the input data gotten from the actual test data as shown in Table 1 Run the Gasturb 11 software and select mixed flow turbofan from the drag down Tab list. Set the scope to More, set the Calculation Mode as Design and click Run Choose the Units to either Imperial or SI and Select the type of fuel from to drop down list to Kerosene, Natural Gas or Hydrogen Estimate the inlet Corrected mc2 Mass Flow rate to the FAN/LPC Choose Single Cycle for Select a chore Option and click Run Check if the Thrust, SFC, ? HPT, ? LPT and EPR are within (0-10) % of the actual test Experiment END YES NO Figure 4 Design Point Cycle Simulation Algorithm Using Gas Turb 11 Verification of the Design Point simulation ResultsSince not all the input parameters were specified in the actual test data and some of them had to be guessed, it is without any doubt that errors are bound to generate in the simulation results using the Gas Turb 11 software. In order to ensure that the errors accumulated in the simulation were within range, the major output parameters obtained such as net thrust, fuel flow rate, Engine exit pressure ratio, etc were compared to the actual test data as shown in Table 2 and the error range was calculated to be between 0. 25% to 8. 5% which is within an acceptable range. PARAMETERS ACTUAL TEST DATA SIMULATED DATA USING GASTURB 11 Net Thrust 69307. 74 69320 Engine Exit Pressure Ratio P8P0 2. 09 2. 167Burner Fuel Flow 1. 100843 1. 09781 HPT pressure Ratio (? HPT) 0. 415 0. 449 LPT Pressure Ratio (? LPT) 0. 3 294 0. 3514 HPT temperature Ratio (? HPT) 0. 8097 0. 8435 LPT temperature Ratio (? LPT) 0. 7718 0. 793 Table 2 Comparison Table for the Actual Test Data and Simulated Data Using GasTurb 11 4. 3. Off-Design Point Cycle Simulation of the Turbofan Engine The off-design or performance cycle simulation takes into account the concept of module twin(a) of each component through performance maps. This cycle analysis enables the determination of different operating point of the engine at a given design point of the engine.Considering the work in hand, the design point have been defined and verified for the JT8D-15A turbofan engine operating at sea level with maximum take-off thrust which means that different operating points of the engine can be defined with the concept of off-design module matching of the engine. Indeed, the off-design operating point that was considered for the parametric analysis in this work was 30,000ft at M0 0. 8 for the turbofan engine. The off-design modelling of th e JT8D-15A engine for the operating point of 30,000ft at M0 0. 8 based on the reference design point defined earlier is clearly demonstrated as follows. The off-design performance cycle simulation may gibe some errors because of the component performance maps that were used for the simulation. 4. 3. 1. Module/Component Matching This process only applies to the off-design performance cycle point of the engine.It can simply be defined as the act of synchronising each component of a jet engine to coexist as a unit in order to derive the overall performance characteristics of the jet engine. Component matching involves the process closely studying the ramifications of the actual jet engine overall performance doings on the components major characteristics such as pressure ratio, temperature ratio, efficiency and spool speed. This process introduces the concept of empirically determined component performance maps that establishes the relationship between the thermodynamic properties an d the geometry of the jet engine itself. 4. 3. 2. Off-Design Component Modelling Diffuser The diffuser was assumed to be adiabatic and the pressure ratio ? d=1 The Isentropic Efficiency was assumed to be 1 For Sea Level,Pamb=101325pa , Tamb=288. 15K For 30,000ft and M0 0. 8, Tamb=288. 15-0. 0065? 9144 =288. 15-59. 436 =228. 71K Pamb=101325? Tamb288. 155. 2561 =30. 09kpa Tt1=228. 71? 1+? -12M02 =228. 71? 1+1. 4-12? 0. 82 =258K pt1p0=1+ ? d? -12M02 -1 pt1=30. 09? 1+ 1? 1. 4-120. 821. 41. 4-1 pt1=45. 8674kPa pt1=pt2 Tt1=Tt2 Fan and Low Pressure Compressor The inlet corrected mass flow rate is estimated as 138. 618kg/s , As for the off design simulation using the component performance maps for the altitude of 30000ft and Mach no. 0. 8, the actual spool speeds and inlet mass flow rate are calculated based on the estimated inlet corrected mass flow rate as shown below.Low and High pressure spool mechanical efficiency is assumed to be=1 HP spool Speed=11420RPM, LP spool Speed=8160RPM m2=Pt 2PSTD? mc2Tt2TSTD =45. 878101. 325? 138. 618258288. 15 Actual Mass flow rate m2=66. 3323kg/s N=Tt2TSTD? NcLP=228. 71288. 15? 8160=7722 RPM The calculated actual mass flow rate and spool speed were used to evaluation the isentropic efficiency and the pressure ratio of the LPC for that operating condition from the compressor performance map. Figure 5 Example of a Compressor Performance Map/Curve The diagram above in figure 4 depicts a typical compressor performance map that was used for the off-design point analysis in this work.It can be seen that the x-axis represents the inlet corrected mass flow rate mc2 into the compressor, the y-axis represents the compressor pressure, the red contour lines represents the isentropic efficiencies and the black curved lines represent the relative corrected spool speed. To add to that, the red dash line that ends the speed lines and efficiency lines represent the surge margin which is also known as the stall line that must be avoided since the flow will become unstable in that region. In this work, the inlet corrected mass flow rate and spool speed were calculated which were interpolated on the performance map to obtain the pressure ratio and the isentropic efficiency.For instance, the yellow dot on the map represents a design point traced for a given pressure ratio, High Pressure Compressor The inlet corrected mass flow rate into the HPC mc2. 5=mc21+? mc2. 5=138. 6182. 08=66. 64kgs m2. 5=Pt2. 5PSTD? mc2. 5Tt2. 5TSTD N=Tt2. 5TSTD? NcHP The same equation used for the LPC is used to calculate the actual mass flow rate and spool speed which is used to evaluate the isentropic efficiency and pressure ratio when it is operating at an altitude of 30000ft at M0 =0. 8. Verification of the off-design modelling for 30000ft at Mo 0. 8 In order to verify the simulation result gotten for the operational design point of 30000ft at M0 0. , the actual test data results gotten from Mattingly, Heiser and Pratt (2002) for the same operating cond ition was compared. Due to the difficulties in obtaining a lot of output parameters for this operating point, the result will be verified with only the net thrust generated and the specific fuel consumption. Indeed, the error accumulated was 1. 71% for the net thrust and 0. 83% for the specific fuel consumption. PARAMETERS ACTUAL TEST DATA SIMULATED DATA USING GASTURB 11 Net Thrust (lb) 4920 4836 Specific Fuel Consumption(lb/lbh) 0. 779 0. 7855 Table 3 Comparison Table for the Actual Test Data and Simulated Off-design Data Using GasTurb 11 Chapter 5Methodology, Results and Discussions Given that the design point of the JT8D-15A turbofan engine at sea level has been obtained and verified with the actual test data, the operating point of 30000ft at M0 0. 8 was simulated and obtained which now served as the design point for the analysis in this work. Moreover, the procedure taken to define this design point of 30000ft at M0 0. 8 of the JT8D-15A turbofan engine has been clearly stated e arlier which gives the permission to conduct the parametric cycle study of the turbofan engine. The parametric cycle studies were done for three different cases for the operational design point of 30000ft at M0 0. of the JT8D-15A turbofan engine as explained as follows. 1. The first parametric analysis case 1 aim to create an understanding of the effects of varying major design parameters on the performance parameters of the turbofan engine when some of the design choices are kept constant. In other words, the bypass ratio and thermal limit parameter (turbine inlet temperature) were varied when the design choices such as the compressor pressure ratio, fan pressure ratio and isentropic efficiencies were kept constant in order to investigate their effects on the performance parameters such as the net thrust, specific fuel consumption, propulsive efficiency, thermal efficiency, and fuel-air-ratio.Much interest is shown nowadays in using alternative fuels like hydrogen and Natural gas i n efforts to reduce the cancer known as pollution and the risk of depletion of energy resources. Based on this, conducting a research that focuses of comparing different fuels consumption rate, their risk of pollution and their contribution to the performance of the engine will be really valuable. Based on this, a parametric analysis had to be done on the JT8D-15A turbofan engine using three different fuels which are the design point fuel kerosene, hydrogen and natural gas. Since the original design point of the JT8D-15A turbofan was obtained using kerosene fuel, the design points of using hydrogen and natural gas was obtained using the same design choices as that of kerosene.Now that the design points of the JT8D-15A turbofan engine had been defined when using the three different fuels, it had given a go ahead to perform whatever parametric cycle studies of the turbofan engine using the three fuels. In order to compare the performance characteristics of the turbofan engine when it is using the three different fuels, different approaches had to be devised to compare them effectively on a rational basis which defines the last two parametric analysis cases as follows. 2. The second case of parametric analysis was that the fuel flow rate would be kept constant for the three fuels that would be used as the bypass ratio is varied with design choices remaining the same. 3.The third case of study was to make the energy supply into the combustion chamber of the turbofan engine the sa

Concept and Nature Essay

1. Introduction Chapter 1. Concept- a impulse or statement of an idea 2. 1 A judgment is a heavy category of existence. 2. 2 oncepts as mandated by a particular mental conjecture active the state of the mankind. 2. 3 A concept is a public feature or characteristic 2. 4 The nonion of sense as identical to the notion of concept 1. A general idea derived or inferred from ad hoc instances or occurrences. 2. Something formed in the mind a thought or notion. See Synonyms at idea. 3.A scheme a plan began searching for an part to handle a new restaurant concept(ADWEEK). 1. an idea, esp an abstract idea the concepts of biology 2. ( philosophical system) Philosophy a general idea or notion that equalizes to few class of entities and that consists of the characteristic or essential features of the class 3. (Philosophy) Philosophy a. the conjunction of altogether the characteristic features of almostthing b. a theoretical construct within nearly theory c. a directly intuited objec t of thought d. the importation of a predicate 4.(Engineering / Automotive Engineering) (modifier) (of a point of intersection, esp a car) created as an exercise to establish the technical skills and imagination of the designers, and not intended for mass production or sale from Latin conceptum approximatelything received or conceived, from concipere to take in, conceive A notion or statement of an idea, expressing how something might be d nonpargonil or accomplished, that may lead to an accepted procedure. concept noun idea, view, image, theory, impression, notion, conception, hypothesis, abstraction,conceptualization She landed that the concept of arranged marriages is misunderstood in the west. ball side Dictionary concept (? k? ns? pt) n 1. idea, especi all in ally an abstract idea the concepts of biology 2. philosophy a general idea or notion that corresponds to some classof entities and hat consists of the characteristic or essentialfeatures of the class 3. . philo sophy a. the conjunction of all the characteristic features of something b. a theoretical construct within some theory c. a directly intuited object of thought d. the meaning of a predicate4. ( modifier ) (of a product, esp a car) created as an exercise todemonstrate the technical skills and imagination of the designers,and not intended for mass production or sale C16 from Latin conceptum something received or conceived, fromconcipere to take in, conceive A. In general usage the term chiefly denotes idea or notion. It is envisaged as an abstract or psycho dianoetic thing presupposing conscious minds which at least potentially feed the concept, i. e. , understand it, lam with it, apply it, etc.In philosophy and the social cognitions (and otherwise sciences too) concepts enter as (a) the most general tools of inquiry as such(prenominal) and as (b) the limit or object of some specific inquiries, notably in comparative studies. What follows refers principally to (a) rather than (b). The genius of concepts, and their relation to the things of which they atomic number 18 the concepts, and to the minds which use or study them, be among the most hotly disputed subject in philosophy. The present definition is not intended to prejudge or settle any of these issues, as yet if l fictives of space make it appear to do so.B. Defined as an aspect of thought, a concept is a kind of unit in scathe of which atomic number 53 thinks a unit smaller than a judgement, proposition, or theory, but one which necessarily enters into these. In an assertion, something is predicated of a concept, and the predicate itself can generally be re-described as a concept. At the same time, however, the concept is by no means an ultimate or indivisible unit, for concepts can be augmented or change magnitude by addition or subtraction of some feature.(For instance, one may say that someones concept of social class does, or fails to, complicate the notion of differences in mat erial rewards. ) Moreover, while concepts occur within assertions or theories and are thus distinct from them, a proposition or theory or thesis as a full-duration can in turn be referred to as a further concept. For instance, R. Firth writes that some of Dr. Leachs concepts are of a special orderI refer to his thesis that seeking for power is the basis of social choice (Fore sacred scripture to E. R. Leach, Political Systems of Highland Burma, London G. Bell, 1954, p. vii). C.Concepts correspond to or are the meaning of all meaningful words, with certain qualifications (a) but one concept corresponds to 2 or more words with the same meaning (b) in that location is a tendency to speak of concepts altogether with regard to words which do, or at least can, refer either to something that can exist or be imagined or to an operation that can be performed, and not in connection with words whose role is grammatical rather than designative (for instance, one may speak of the concept o f sovereignty, of infinity, of addition, but not of the concept of and though one must add that the drawing of the lines beetween these kinds of meaning is difficult, unsettled, and controversial part of philosophy(c) there is a tendency to speak of concepts in connection with general rather than singular term (one is un handlely to speak of a concpet of John or of a concpet of London in those cases the term conception is more similarly to be used. There are, however, exceptions, e. g. , the concept of God).The fact that concepts may be seen as the meanings of terms should not lead one to suppose that concepts are in some narrow sense linguistic entities although concepts may be pay backd in terms of the rules governing the use of the words said to designate them, those rules determine (a) what things in the military personnel race are classed together (as falling under the same concept), (b) what features are grouped together (as being various characteristics of the same thing ), (c) what operations of measurement, classification, discrimination, etc. , are performed by the man using the concept, and so on. D.Discussions of concepts in the social sciences tend to be a matter of the choice of terms and, more importantly, of their definitions. One may talk both of discovering and of inventing concepts alike of changing and developing concepts. In as far as given theories require certain concepts, and in as far as concepts can be said to incorporate theories, there is no sharp line between choice of theories and choice of concepts.Nevertheless, whole theories are thought of primarily as true or false, concepts are more of course described as applicable or inapplicable, valid or invalid, useful or useless. Taken from A Dictionary of the Social Sciences eds. J. Gould and W. Kolb, acquit Press, 1964. Concept From Wikipedia, the free encyclopedia In metaphysics, and especially ontology, a concept is a fundamental category of existence. In contemporary philo sophy, there are at least three prevailing ways to understand what a concept is1 Concepts as mental representations, where concepts are entities that exist in the brain. Concepts as abilities, where concepts are abilities odd to cognitive agents. Concepts as abstract objects, where objects are the constituents of propositions that mediate between thought, language, and referents.Concepts were natural out of the rejection of some or all of the classical theory,4 it seems appropriate to give an flier of what might be wrong with this theory. In the 20th century, philosophers such as Rosch and Wittgenstein argued against the classical theory. There are six primary arguments4 summarized as follows It seems that there manifestly are no definitions especially those based in sensory primitive concepts. 4 It seems as though there can be cases where our ignorance or error about a class means that we either dont know the definition of a concept, or have incorrect notions about what a defi nition of a particular concept might entail.4 Quines argument against analyticity in Two Dogmas of Empiricism also holds as an argument against definitions. 4 Some concepts have addled membership. There are accompaniments for which it is vague whether or not they fall into (or out of) a particular referent class. This is not possible in the classical theory as e reallything has equal and full membership. 4 Rosch found typicality effects which cannot be explained by the classical theory of concepts, these sparked the prototype theory. 4 See below. Psychological experiments show no point for our using concepts as strict definitions. 4 Prototype theory Main article Prototype theory Prototype theory came out of problems with the classical view of conceptual structure.1 Prototype theory says that concepts specify properties that members of a class tend to possess, rather than must possess. 4 Wittgenstein, Rosch, Mervis, Berlin, Anglin and Posner are a few of the key proponents and cre ators of this theory. 45 Wittgenstein describes the relationship between members of a class as family resemblances. There are not necessarily any necessary conditions for membership, a weenie can still be a dog with that three legs. 3 This view is particularly supported by psychological experimental evidence for prototypicality effects. 3 Participants pull up stakesingly and consistently rate objects in categories like vegetable or furniture as more or less typical of that class.35 It seems that our categories are fuzzy psychologically, and so this structure has explanatory power. 3 We can judge an items membership to the referent class of a concept by canvass it to the typical member the most central member of the concept. If it is similar full in the relevant ways, it will be cognitively admitted as a member of the relevant class of entities. 3 Rosch suggests that every category is represented by a central exemplar which embodies all or the maximum possible number of feature s of a given category. 3 Theory-theory Theory-theory is a reaction to the previous two theories and develops them further. 3 This theory postulates that classification by concepts is something like scientific theorizing.1 Concepts are not seeed in isolation, but rather are learned as a part of our experiences with the world around us. 3 In this sense, concepts structure relies on their relationships to other concepts as mandated by a particular mental theory about the state of the world. 4 How this is supposed to cash in ones chips is a little less clear than in the previous two theories, but is still a prominent and notable theory. 4 This is supposed to explain some of the issues of ignorance and error that come up in prototype and classical theories as concepts that are structured around each other seem to ac wager for errors such as whale as a fish (this misconception came from an incorrect theory about what a whale is like, combining with our theory of what a fish is).4 When we learn that a whale is not a fish, we are recognizing that whales dont in fact fit the theory we had about what makes something a fish. In this sense, the Theory-Theory of concepts is responding to some of the issues of prototype theory and classic theory. 4 Issues in concept theory A priori concepts Main articles A priori and a posteriori and Category (Kant) Kant declared that human minds possess uncontaminated or a priori concepts. Instead of being abstracted from individual perceptions, like empirical concepts, they originate in the mind itself. He called these concepts categories, in the sense of the word that means predicate, attribute, characteristic, or quality.But these pure categories are predicates of things in general, not of a particular thing. According to Kant, there are 12 categories that constitute the mind of phenomenal objects. Each category is that one predicate which is common to multiple empirical concepts. In order to explain how an a priori concept can un ite to individual phenomena, in a manner analogous to an a posteriori concept, Kant employed the technical concept of the schema. Immanuel Kant held that the account of the concept as an abstraction of experience is only partly correct. He called those concepts that takings from abstraction a posteriori concepts (meaning concepts that arise out of experience).An empirical or an a posteriori concept is a general representation (Vorstellung) or non-specific thought of that which is common to several specific perceived objects (Logic, I, 1. , 1, Note 1) A concept is a common feature or characteristic. Kant investigated the way that empirical a posteriori concepts are created. The logical acts of the understanding by which concepts are generated as to their form are comparison, i. e. , the likening of mental images to one another in relation to the unison of consciousness reflection, i. e. , the going back over different mental images, how they can be comprehended in one consciousness and finally abstraction or the segregation of everything else by which the mental images differ In order to make our mental images into concepts, one must thus be able to compare, reflect, and abstract, for these three logical operations of the understanding are essential and general conditions of generating any concept whatever. For example, I see a fir, a willow, and a linden. In originly comparing these objects, I notice that they are different from one another in respect of trunk, branches, leaves, and the like further, however, I reflect only on what they have in common, the trunk, the branches, the leaves themselves, and abstract from their size, shape, and so forth thus I gain a concept of a tree. Embodied content Main article Embodied science In cognitive linguistics, abstract concepts are transformations of concrete concepts derived from embodied experience.The mechanism of transformation is structural part, in which properties of two or more source domains are selectiv ely mapped onto a blended space (Fauconnier & Turner, 1995 see conceptual blending). A common class of blends are metaphors. This theory contrasts with the rationalist view that concepts are perceptions (or recollections, in Platos term) of an independently existing world of ideas, in that it denies the existence of any such realm. It also contrasts with the empiricist view that concepts are abstract generalizations of individual experiences, because the contingent and sensible experience is preserved in a concept, and not abstracted absent.While the perspective is compatible with Jamesian pragmatism, the notion of the transformation of embodied concepts through structural mapping makes a distinct contribution to the problem of concept formation. citation needed Ontology Plato was the starkest proponent of the realist thesis of universal concepts. By his view, concepts (and ideas in general) are innate ideas that were instantiations of a transcendental world of pure forms that lay behind the veil of the physical world. In this way, universals were explained as transcendent objects. Needless to say this form of realism was tied deeply with Platos ontological projects. This remark on Plato is not of merely historical interest.For example, the view that numbers are Platonic objects was revived by Kurt Godel as a result of certain puzzles that he took to arise from the phenomenological accounts. Gottlob Frege, founder of the analytic tradition in philosophy, famously argued for the analysis of language in terms of sense and reference. For him, the sense of an face in language describes a certain state of affairs in the world, namely, the way that some object is presented. Since many another(prenominal) commentators view the notion of sense as identical to the notion of concept, and Frege regards senses as the linguistic representations of states of affairs in the world, it seems to follow that we may understand concepts as the manner in which we grasp the worl d.Accordingly, concepts (as senses) have an ontological status (Morgolis7) According to Carl Benjamin Boyer, in the introduction to his The History of the Calculus and its Conceptual Development, concepts in calculus do not refer to perceptions. As keen-sighted as the concepts are useful and mutually compatible, they are accepted on their own. For example, the concepts of the derivative and the integral are not considered to refer to spatial or temporary perceptions of the external world of experience. Neither are they related in any way to mysterious limits in which quantities are on the verge of nascence or evanescence, that is, coming into or going out of existence.The abstract concepts are now considered to be totally autonomous, even though they originated from the move of abstracting or taking away qualities from perceptions until only the common, essential attributes remained. Etymology The term concept is traced back to 155460 (Latin conceptum something conceived), but w hat is today termed the classical theory of concepts is the theory of Aristotle on the definition of terms. citation needed The meaning of concept is explored in mainstream information science, cognitive science, metaphysics, and philosophy of mind. In computer and information science contexts, especially, the term concept is often used in unclear or inconsistent ways.When writing on the idea of constitution as both stable in meaning and of the exchangeability of disposition for other conceptualizations in pen works, one should probably define temperament in a definite way as to allow for comparisons in meaning. When seeking to define record, whether it be of a human sort or any other, one must consider the parts to fully understand the whole. Everything must have a nature. If nothing had a nature, would that mean nature as we think of it would cease to exists? Or would we have another name for it? When seeking to define nature, there are a few routes to consider. Does a bear h ave a personality or a nature? Or both? When a bear frolics and plays, is that personality or nature? When it hibernates, is that personality or nature?For the sake of this argument, we shall say that when a bear happens to be frolicking and playing, he is doing so in a certain style, or way that is unique to that bear that sets him apart from his fellows, but not so much so that it alienates him from all bears. From there, we will assume this is because its personality allows it to. When it hibernates, it is because nature forces it to. temper therefore is uniform it has no uniqueness within bear kind. So establishing that a bear has a personality and a nature, what does this mean for criticism? practically in our readings we see references to nature, such as Mother Nature, human nature, the nature of plays and poetry, and so on and so forth.The question then, is what does a critic refer to when he says nature? Is he referring to hibernation? Or has he meant that nature is all-en compassing, referring to all actions of the bear as nature? As we have defined an instance of personality and nature within the inner workings of the bear, likewise must be done within the workings of criticism. In An Essay of Dramatic Poesy John Dryden states that a play ought to be, a just and lively image of human nature, representing its passions and humors, and the changes of fortune to which it is subject for the delight and instruction of mankind. When he mentions human nature here, he is referring to many things at once.He is connecting the emotions one feels (passion and humors), that could easily be said to be part of an individuals personality, as well as the commonality we all share in that there are no unique emotions to any one person. No one person has only felt happiness their whole life, nor has anyone not experience happiness at all. Drydens mention of the changes of fortune requires the alteration of the definition of nature we have thus far defined. When conside ring the bear, we didnt count events in the bears life as part of his nature or personality. One can, however, predict what the bear will do in a life-changing event based on what we know of his nature. When it beings to get colder, a bear, as mandated by his bear nature, will forage for food to prepare for hibernation. When winter comes he will find a cave and hibernate.So when Dryden says the change of fortune to which it is subject, it can be assumed he means that human nature will react in a certain and specific and mostly predictable way to changes in the fictional characters life. This means we can add an element of predictability and stability of actions to the definition of nature, with any variation given to personality. Dryden then turns to the notion of pretended. He speaks of imitating the ancient Greeks, who were imitators of nature. He speaketh Those Ancients have been near imitators and wise observers of that nature which is so torn and ill represented in our plays. This statement leads us to believe that nature is something to be notice and imitated.Therefore if one wanted to flop portray a day in the life of our bear, he would watch the bear play, fish, sleep, and ect. The artist would then consider all of this as the bears nature, and imitate it on the stage or on paper in a story. The same process is therefore used when seeking to observe human nature. The poet, the playwright, the artist and novelist must be vigilant, claims Dryden, when observant so that when it is time to imitate, he can do so accurately. Aristotle, of the aforementioned Ancients, also discussed at great length the importance of the imitation of nature in art in his essay Poetics . Aristotlestates Speaking generally, the origin of the art of poetry is to be found in two natural causes.For the process of imitation is natural to mankind from childhood on Man is differentiated from other animals because he is the most imitative of them, and he learns his first lessons t hrough imitation, and we observe that all men find pleasure in imitations. Imitation is considered here by Aristotle to be natural to mankind, even being so bold as to claim only humans learn from imitation. This natural tendency to imitate therefore leads us to find pleasure in observing imitations as well the act of imitation itself. Aristotle then incorporates imitation as a part of human nature, meaning that the action of imitation and the enjoyment of imitation is something all humans participate in, much in the way all bears hibernate in the winter. Aristotle continues by sayingSince imitation is given to us by naturemen, having been naturally endowed with these gifts from the beginning and then developing them gradually, for the most part, finally created the art of poetry from their early improvisations. Poetry then diverged in the directions of the natural dispositions of the poets. At this point, Aristotles notion of nature gets a little vague. First he states that imitati on comes to mankind naturally. As he continues, however, he states that imitation is then developed, like a skill not an instinct. This concept evolves further to say that only the likes of poets become masters of imitation. Poets are unique in their ability to portray the observations of imitations they see.This uniqueness removes them from our definition of what is natural and applies to humans as a species, as Aristotle claims earlier. What Aristotle is applying here is another version of nature that is microsphere-ish to an individual, hence personality. Aristotle does not make this distinction what-so-ever. If imitation comes naturally to mankind as a whole, yet poetry only comes naturally to the disposition of poets, what exactly does that mean when defining nature? It means the terms nature and naturally in this passage needs footnotes. Perhaps when looking at this passage in terms of the way the words nature and naturally are used, Aristotle first uses it to refer to a unive rsal characteristic shared by all humans imitation.When refereeing to the poet, however, the definition changes slightly to refer to only poets, as though they are their own sub-species. An equivalent statement would be All bears hibernate, but black bears hibernate the best. Longinus also had an opinion of nature in his work On The Sublime. A lofty tone, says one, is innate, and does not come by teaching nature is the only are that can compass it. Works of nature are, they think, made worse and altogether feebler when wizened by the rules of art. But I maintain that this will be found to be otherwise if it be observed that, while nature as a rule is free and independent in matters of passion and elevation, yet is she wont not to act at hit-or-miss and utterly without system.Further, nature is the original and vital underlying principle in all cases, but system can define limits and fitting seasons, and can also contribute the safest rules for use and practice. Longinus starts his argument out by saying what others have been saying that the ability to write well comes from a persons natural talent one that is born and not cultivated. Moreover, art is less sublime when confined to rules of art. Longinus argues this point, saying that if one truly observes an artist, they will find that while a natural born talent is a key principle, there is a system and structure to what is considered safe art that is outside of natures control, which is contrary to the believe say first.Longinus continues his argument by saying This we may apply to diction, nature occupying the position of good fortune, art that of good counsel. Most important of all, we must remember that the very fact that there are some elements of expression which are in the hands of nature alone, can be learnt from no other sources than art. Longinus argues that ultimately nature is a catalyst for creation but does not play a role when judging if what has been created is becoming enough to be consid ered art. Yet in the undermentioned statement, he gives nature, the credit for the elements of expression that are observed and imitated in art to gain a better understanding of nature itself.When it comes to critiquing art, Drydens argument in An Essay of Dramatic Poesy is that in order for a work of art to be art, it must be the closet to actual nature. Ancients have been faithful imitators and wise observers of that nature which is so torn and ill represented in our plays they have handed down to us a perfect resemblance of her which we, like ill copiers, neglecting to look on, have rendered monstrous, and disfigured. When plays or writings dont give an exact replication of nature, or even what is considered human nature, it loses value. It cannot be considered good art. The Greeks gave us examples of what good art is with their philosophies and ideas about nature and human nature. One advantage Dryden mentions his time period has over the Greeks is the advancement of science.H e says Is it not evident, in these last hundred years (when the study of philosophy has been the business of all the virtuosi in Christendom) that almost a new nature has been revealed to us? That more errors of the condition have been detected, more useful experiments in philosophy have been made, more noble secrets in optics, medicine, anatomy, astronomy, find, than in all those credulous and doting ages from Aristotle to us? O true it is that nothing spreads more fast than science, when rightly and generally cultivated. As far as Dryden is concerned, that while many virtuous men have been cerebrate on philosophy, the times since Aristotle have changed. The invention of the microscope and the discovery of cells have altered how the natural world is viewed.There is more to everything in nature that meets the eye. He notes that worthy experiments in philosophy have been made, but that the rapid expanse of information generated by science has eclipsed those of philosophy. As there are no such references to science in regards to philosophy in Aristotles time, the philosopher of today must make his own way in regards to managing the way sciences has changed our view of nature. But what does science have to do with philosophy and art? The answer lies in the nature of art to reflect and imitate nature. Now that the secrets of optics, medicine, anatomy, and astronomy have been revealed, our human nature takes these secrets in.Philosophy now must contend and compromise with how these advancements fit into the human condition. The new nature must be negotiated with in terms of how it affects our lives. And of course science gives imitators a new genera in which to work. Painters can now paint the surgeon at work, perhaps teaching pupils. Once something becomes a natural experience, including that of science, it is to be imitated by poets. Nature, in its ever shifting meanings, does seem to have one consistent idea contributed to it, despite the technicalities. It c an refer to the literal, organic substances that make up the vegetation, animals, and mankind in the world around us.It can also mean the behavior exhibited by said organic beings, such as the hibernation of bears. It has also been used to describe the emotions and other commonalties experienced by humans as a whole. Aristotle and Dryden have made it clear that within mankind there are certain characteristics attributed by nature, such as the observation and imitation of that which is around us. Simply put, it is in our nature to imitate nature. However, this definition of nature is refined when it comes under the consideration of art. While all of mankind takes delight in imitation, nature has endowed the artist, like say the poet, with a more natural and superior sense of imitation.When it comes to critiquing art of any sort, association and a developed set of skills replaces nature according to Longinus. The act of imitating and creating may have natural causes, but the ability to ascribe worth to these creations can only come from a refined sense of what is makes good art, something that is not obtained from nature. In Drydens opinion, only the closest of imitations of nature are art. He also relies on the philosophy and insight into human nature of the ancient Greeks to guide what is valuable when it comes to art. Dryden makes the effort to include science in his argument by stating that science has discovered a new nature that will be observed and imitated and philosophized that the Greeks had no knowledge of.Nature, therefore, is still evolving, as will our concept of the many definitions of Nature. The idea of nature is one of the most widely employed in philosophy, and by the same token one of the most ill-defined. Authors such as Aristotle and Descartes relied on the concept of nature to explain the fundamental tenets of their views, without ever attempting to define the concept. Even in contemporary philosophy, the idea is oftentimes employed, in d ifferent forms. So, what is nature? Nature and the Essence of a Thing The philosophical tradition that traces back to Aristotle employs the idea of nature to explain that which defines the essence of a thing.One of the most fundamental metaphysical concepts, the essence indicates those properties that define what a thing is. The essence of water, for instance, will be its molecular structure, the essence of a species, its ancestral history the essence of a human, its self-consciousness or its soul. at heart the Aristotelian traditions, hence, to act in accordance with nature means to take into account the real definition of each thing when dealing with it. The Natural World At times the idea of nature is instead used to refer to anything that exists in the universe as part of the physical world. In this sense, the idea embraces anything that travel under the study of the natural sciences, from physics to biology to environmental studies. Natural vs.ArtificialNatural is often used also to refer to a process which occurs spontaneously as opposed to one that occurs as the result of the deliberation of a being. Thus, a plant grows naturally when its growth was not planned by a rational agent it grows otherwise artificially. An apple, would hence be an artificial product, under this understanding of the idea of nature, although most would agree that an apple is a product of nature (that is, a part of the natural world, that which is studied by natural scientists). Nature vs. Nurture Related to the spontaneity vs. artificiality divide is the idea of nature as opposed to nurture.