DOCSLIB.ORG

A Design Study of Single-Rotor Turbomachinery Cycles

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

A Design Study of Single-Rotor Turbomachinery Cycles by Manoharan Thiagarajan A thesis submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering Committee Dr. Peter King, Chairman Dr. Walter O’Brien, Committee Member Dr. Clint Dancey, Committee Member August 12, 2004 Blacksburg, Virginia Keywords: Auxiliary power unit, single radial rotor, specific power takeoff, compressor, burner, turbine A Design Study of Single-Rotor Turbomachinery Cycles by Manoharan Thiagarajan Dr. Peter King, Chairman Dr. Walter O’Brien, Committee Member Dr. Clint Dancey, Committee Member (ABSTRACT) Gas turbine engines provide thrust for aircraft engines and supply shaft power for various applications. They consist of three main components. That is, a compressor followed by a combustion chamber (burner) and a turbine. Both turbine and compressor components are either axial or centrifugal (radial) in design. The combustion chamber is stationary on the engine casing. The type of engine that is of interest here is the gas turbine auxiliary power unit (APU). A typical APU has a centrifugal compressor, burner and an axial turbine. APUs generate mechanical shaft power to drive equipments such as small generators and hydraulic pumps. In airplanes, they provide cabin pressurization and ventilation. They can also supply electrical power to certain airplane systems such as navigation. In comparison to thrust engines, APUs are usually much smaller in design. The purpose of this research was to investigate the possibility of combining the three components of an APU into a single centrifugal rotor. To do this, a set of equations were chosen that would describe the new turbomachinery cycle. They either were provided or derived using quasi-one-dimensional compressible flow equations. A MathCAD program developed for the analysis obtained best design points for various cases with the help of an optimizer called Model Center. These results were then compared to current machine specifications (gas turbine engine, gasoline and diesel generators). The result of interest was maximum specific power takeoff. The results showed high specific powers in the event there was no restriction to the material and did not exhaust at atmospheric pressure. This caused the rotor to become very large and have a disk thickness that was unrealistic. With the restrictions fully in place, they severely limited the performance of the rotor. Sample rotor shapes showed all of them to have unusual designs. They had a combination of unreasonable blade height variations and very large disk thicknesses. Indications from this study showed that the single radial rotor turbomachinery design might not be a good idea. Recommendations for continuation of research include secondary flow consideration, blade height constraints and extending the flow geometry to include the axial direction. Acknowledgement The author wishes to express his sincere gratitude to Dr. Peter King, major professor, for contributing valuable time, advice, and assistance to the research and to the preparation of this manuscript. Sincere thanks are due to the members of the author’s graduate committee composed of Dr. Walter O’Brien, and Dr. Clint Dancey for their advice and constructive criticism. The author also is grateful to Phoenix Integration for allowing him to use Model Center for the purpose of optimization to help in the completion of this research project. Very special thanks are due to the author’s parents for their understanding, patience, and encouragement throughout the course of this study. Heartiest thanks are also due to Rene Villanueva, An Song Nguyen, and Kevin Duffy for all their encouragement. Special appreciation goes out to Ms. Lisa Stables for all her assistance during this research. To all turbolabbers, warp speed ahead. Space is the final frontier. iii Table of contents TABLE OF FIGURES ............................................................................................................................................VII LIST OF TABLES.................................................................................................................................................... XI NOMENCLATURE .............................................................................................................................................. XIII CHAPTER 1 INTRODUCTION.........................................................................................................................1 1.1 ABOUT SMALL GAS TURBINE ENGINES ..........................................................................................................1 1.2 AUXILIARY POWER UNIT (APU) AND PURPOSE OF RESEARCH .......................................................................4 CHAPTER 2 LITERATURE REVIEW.............................................................................................................6 2.1 HISTORY OF THE APU...................................................................................................................................6 2.1.1 Project A .........................................................................................................................................6 2.1.2 The Black Box .................................................................................................................................6 2.1.3 The GTC43/44.................................................................................................................................8 2.2 IDEAL BRAYTON CYCLE AND IDEAL JET PROPULSION CYCLE........................................................................9 2.3 HOW CURRENT APUS WORK.......................................................................................................................11 CHAPTER 3 FORMULAS USED FOR THE APU ........................................................................................15 3.1 GENERAL INFORMATION .............................................................................................................................15 3.2 AMBIENT AIR AND DIFFUSER.......................................................................................................................17 3.3 COMPRESSOR ..............................................................................................................................................18 3.4 BURNER AND TURBINE................................................................................................................................22 3.4.1 Burner equations...........................................................................................................................23 3.4.2 Burner input parameters and method of solving equations ..........................................................25 3.4.3 Turbine equations .........................................................................................................................28 3.4.4 Turbine input parameters..............................................................................................................29 3.4.4.1 Subsonic turbine............................................................................................................................................ 30 3.4.4.2 Supersonic turbine ........................................................................................................................................ 31 3.4.5 Method of solving turbine equations.............................................................................................32 3.4.6 Burner and turbine output summary .............................................................................................35 3.5 OVERALL APU PROPERTIES........................................................................................................................37 CHAPTER 4 RESULTS OF ANALYSIS.........................................................................................................39 4.1 SIMPLE ONE-DIMENSIONAL FLOW ...............................................................................................................39 4.1.1 Burner ...........................................................................................................................................40 4.1.1.1 Constant area flow with drag and heat addition ............................................................................................ 40 4.1.1.2 Constant area flow with only heat addition................................................................................................... 41 iv 4.1.2 Variable area flow ........................................................................................................................42 4.2 SINGLE ROTOR APU RESULTS .....................................................................................................................43 4.2.1 Model Center and input/output constraints ..................................................................................43 4.2.2 Results from Model Center............................................................................................................46 4.2.2.1 Case 1: Without the stress and |(P0-P5)/P5| constraints. ................................................................................. 46 4.2.2.2 Case 2: With the stress constraint but without the |(P0-P5)/P5| constraint...................................................... 48 4.2.2.3 Case 3:
Recommended publications
  • Conceptual Design and Structural Analysis of Ground Support Equipment for Handling and Maintenance of Turboshaft Engines•

    Conceptual Design and Structural Analysis of Ground Support Equipment for Handling and Maintenance of Turboshaft Engines•

    Conceptual design and structural analysis of ground support equipment for handling and maintenance of Turboshaft engines• Iván Felipe Rodríguez-Barón a, Jaime Enrique Orduy-Rodríguez a, Brayan Alejandro Rosas-Bonilla b, Jhon b b Sebastián Merchán-Camelo & Edison Jair Bejarano-Sepúlveda a Programa de Ingeniería Aeronáutica, Fundación Universitaria los Libertadores, Bogotá, Colombia: Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Brasil. [email protected], [email protected] b Programa de Ingeniería Aeronáutica, Fundación Universitaria los Libertadores, Bogotá, Colombia [email protected], [email protected], [email protected] Received: November 17th, 2020. Received in revised form: March 3rd, 2021. Accepted: April 6th, 2021. Abstract This paper describes the application of computational modeling and computer-aided design (CAD) for the conceptual design and structural analysis of the maintenance process of Klimov TV3-117 engines at an approved Maintenance, Repair and Overhaul (MRO) facility in Colombia. The main issue is that these engines are difficult to roll and manipulate due to their weight, which ranges between 250 and 350 kg, which causes time and cost overruns for the operator, and delays in the scheduled maintenance times. The solution proposed by this study is the conceptualization and structural feasibility of a prototype of ground support equipment for handling and maintenance of Turboshaft engines, implementation of which could save up to 100 person-hours, which translates into about USD 10,000, since the current process requires four specialists and two inspectors, whereas the modified process would only require one of each. Keywords: Computer-Aided Design (CAD); structural analysis; turboshaft engines; ground support equipment; aeronautical maintenance.
  • CHAPTER 9 Design and Optimization of Turbo Compressors

    CHAPTER 9 Design and Optimization of Turbo Compressors

    CHAPTER 9 Design and optimization of Turbo compressors C. Xu & R.S. Amano Department of Mechanical Engineering, University of Wisconsin-Milwaukee, USA. Abstract A compressor has been refereed to raise static enthalpy and pressure. A successful compressor design greatly benefi ts the performance of the whole power system. Lean design methodologies have been used for industrial power system design. The compressor designs require benefi t to both OEM and customers, i.e. lowest cost for both OEM and end users and high effi ciency in all operating range of the compressor. The compressor design and optimization are critical for the new com- pressor development and compressor upgrade. The design experience and design considerations are also critical for a successful compressor design. The design experience can accelerate compressor lean design process. An optimization pro- cess is discussed to design compressor blades in turbo machinery. The compressor design process is not only an aerodynamic optimization, but structure analyses also need to be combined in the optimization. This chapter discusses an aerodynamic and structure integration optimization process. The design method consists of an airfoil shape optimization and a three-dimensional gradient-based optimization coupled with Navier–Stokes solvers. A model airfoil of a transonic compressor is designed by using this approach, with an effi ciency improvement. Airfoil sections were stacked up to a three-dimensional rotor blade of a compressor. The effi ciency is improved over a wide range of mass fl ow. The results indicate that the optimiza- tion process can provide improved design and can be integrated into a compressor design procedure.
  • Download the Pbs Auxiliary Power Units Brochure

    Download the Pbs Auxiliary Power Units Brochure

    AUXILIARY POWER UNITS The PBS brand is built on 200 years of history and a global reputation for high quality engineering and production www.pbsaerospace.com AUXILIARY POWER UNITS by PBS PBS AEROSPACE Inc. with headquarters in Atlanta, GA, is the world’s leading manufacturer of small gas turbine propulsion and power products for UAV’s, target drones, small missiles and guided munitions. The demonstrated high quality and reliability of PBS gas turbine engines and power systems are refl ected in the fact that they have been installed and are being operated in several thousand air vehicle systems worldwide. The key sector for PBS Velka Bites is aerospace engineering: in-house development, production, testing, and certifi cation of small turbojet, turboprop and turboshaft engines, Auxiliary Power Units (APU), and Environmental Control Systems (ECS) proven in thousands of airplanes, helicopters, and UAVs all over the world. The PBS manufacturing program also includes precision casting, precision machining, surface treatment and cryogenics. Saphir 5 Safir 5K/G MI Saphir 5F Safir 5K/G MIS Safir 5L Safir 5K/G Z8 PBS APU Basic Parameters Basic parameters APU MODEL Electrical power Max. operating Bleed air fl ow Weight output altitude Units kVA, kW lb/min lb ft 70.4 26,200 S a fi r 5 L 0 kVA 73 → Up to 60 kVA of electric power Safír 5K/G Z8 40 kVa N/A 113.5 19,700 output Safi r 5K/G MI 20 kVa 62.4 141 19,700 Up to 70.4 lb/min of bleed air flow Safi r 5K/G MIS 6 kW 62.4 128 19,700 → Main features of PBS Safi r 5 product line → Simultaneous supply of electric
  • Propeller Operation and Malfunctions Basic Familiarization for Flight Crews

    Propeller Operation and Malfunctions Basic Familiarization for Flight Crews

    PROPELLER OPERATION AND MALFUNCTIONS BASIC FAMILIARIZATION FOR FLIGHT CREWS INTRODUCTION The following is basic material to help pilots understand how the propellers on turbine engines work, and how they sometimes fail. Some of these failures and malfunctions cannot be duplicated well in the simulator, which can cause recognition difficulties when they happen in actual operation. This text is not meant to replace other instructional texts. However, completion of the material can provide pilots with additional understanding of turbopropeller operation and the handling of malfunctions. GENERAL PROPELLER PRINCIPLES Propeller and engine system designs vary widely. They range from wood propellers on reciprocating engines to fully reversing and feathering constant- speed propellers on turbine engines. Each of these propulsion systems has the similar basic function of producing thrust to propel the airplane, but with different control and operational requirements. Since the full range of combinations is too broad to cover fully in this summary, it will focus on a typical system for transport category airplanes - the constant speed, feathering and reversing propellers on turbine engines. Major propeller components The propeller consists of several blades held in place by a central hub. The propeller hub holds the blades in place and is connected to the engine through a propeller drive shaft and a gearbox. There is also a control system for the propeller, which will be discussed later. Modern propellers on large turboprop airplanes typically have 4 to 6 blades. Other components typically include: The spinner, which creates aerodynamic streamlining over the propeller hub. The bulkhead, which allows the spinner to be attached to the rest of the propeller.
  • Low Temperature Environment Operations of Turboengines

    Low Temperature Environment Operations of Turboengines

    0 Qo B n Y n 1c AGARD 2 ADVISORY GROUP FOR AEROSPACE RESEARCH & DEVELOPMENT 3 7 RUE ANCELLE 92200 NEUILLY SUR SEINE FRANCE AGARD CONFERENCE PROCEEDINGS 480 Low Temperature Environment Operations of Turboengines (Design and User's Problems) Fonctionnement des Turborkacteurs en Environnement Basse Tempkrature (Problkmes Pos& aux Concepteurs et aux Utilisateurs) processed I /by 'IMs ..................signed-...............date .............. NOT FOR DESTRUCTION - NORTH ATLANTIC TREATY ORGANIZATION I Distribution and Availability on Back Cover AGARD-CP-480 --I- ADVISORY GROUP FOR AEROSPACE RESEARCH & DEVELOPMENT 7 RUE ANCELLE 92200 NEUILLY SUR SEINE FRANCE AGARD CONFERENCE PROCEEDINGS 480 Low Temperature Environment Operations of Turboengines (Design and User's Problems) Fonctionnement des TurborLacteurs en Environnement Basse Tempkrature (Problkmes PoSes aux Concepteurs et aux Utilisateurs) Papers presented at the Propulsion and Energetics Panel 76th Symposium held in Brussels, Belgium, 8th-12th October 1990. - North Atlantic Treaty Organization --q Organisation du Traite de I'Atlantique Nord I The Mission of AGARD According to its Chartcr, the mission of AGARD is to bring together the leading personalities of the NATO nations in the fields of science and technology relating to aerospace for the following purposes: -Recommending effective ways for the member nations to use their research and development capabilities for the common benefit of the NATO community; - Providing scientific and technical advice and assistance to the Military Committee
  • Propulsion Systems for Aircraft. Aerospace Education II

    Propulsion Systems for Aircraft. Aerospace Education II

    . DOCUMENT RESUME ED 111 621 SE 017 458 AUTHOR Mackin, T. E. TITLE Propulsion Systems for Aircraft. Aerospace Education II. INSTITUTION 'Air Univ., Maxwell AFB, Ala. Junior Reserve Office Training Corps.- PUB.DATE 73 NOTE 136p.; Colored drawings may not reproduce clearly. For the accompanying Instructor Handbook, see SE 017 459. This is a revised text for ED 068 292 EDRS PRICE, -MF-$0.76 HC.I$6.97 Plus' Postage DESCRIPTORS *Aerospace 'Education; *Aerospace Technology;'Aviation technology; Energy; *Engines; *Instructional-. Materials; *Physical. Sciences; Science Education: Secondary Education; Textbooks IDENTIFIERS *Air Force Junior ROTC ABSTRACT This is a revised text used for the Air Force ROTC _:_progralit._The main part of the book centers on the discussion -of the . engines in an airplane. After describing the terms and concepts of power, jets, and4rockets, the author describes reciprocating engines. The description of diesel engines helps to explain why theseare not used in airplanes. The discussion of the carburetor is followed byan explanation of the lubrication system. The chapter on reaction engines describes the operation of,jets, with examples of different types of jet engines.(PS) . 4,,!It********************************************************************* * Documents acquired by, ERIC include many informal unpublished * materials not available from other souxces. ERIC makes every effort * * to obtain the best copravailable. nevertheless, items of marginal * * reproducibility are often encountered and this affects the quality * * of the microfiche and hardcopy reproductions ERIC makes available * * via the ERIC Document" Reproduction Service (EDRS). EDRS is not * responsible for the quality of the original document. Reproductions * * supplied by EDRS are the best that can be made from the original.
  • CHAPTER 10 Advances in Understanding the Flow in A

    CHAPTER 10 Advances in Understanding the Flow in A

    CHAPTER 10 Advances in understanding the fl ow in a centrifugal compressor impeller and improved design A. Engeda Turbomachinery Lab, Michigan State University, USA. Abstract The last 60 years have seen a very high number of experimental and theoretical studies of the centrifugal impeller fl ow physics at government, industry and uni- versity levels, which have been extensively documented. As Robert Dean, one of the well-known impeller aerodynamists stated, “The centrifugal impeller is prob- ably the most complex fl uid machine built by man”. Despite this, it is still the widest used turbomachinery and continues to be a major research and develop- ment topic. Computational fl uid dynamics has now matured to the point where it is widely accepted as a key tool for aerodynamic analysis. Today, with the power of modern computers, steady-state solutions are carried out on a routine basis, and can be considered as part of the design process. The complete design of the impeller requires a detailed understanding of the fl ow in the impeller and aerody- namic analysis of the fl ow path and structural analysis of the impeller including the blades and the hub. This chapter discusses the developments in the understand- ing of the fl ow in a centrifugal impeller and the contributions of this knowledge towards better and advanced impeller designs. 1 Introduction Centrifugal compressors have the widest compressor application area. They are reliable, compact, and robust; they have better resistance to foreign object dam- age; and are less affected by performance degradation due to fouling. They are found in small gas turbine engines, turbochargers, and refrigeration chillers and are used extensively in the petrochemical and process industry.
  • Comparison of Helicopter Turboshaft Engines

    Comparison of Helicopter Turboshaft Engines

    Comparison of Helicopter Turboshaft Engines John Schenderlein1, and Tyler Clayton2 University of Colorado, Boulder, CO, 80304 Although they garnish less attention than their flashy jet cousins, turboshaft engines hold a specialized niche in the aviation industry. Built to be compact, efficient, and powerful, turboshafts have made modern helicopters and the feats they accomplish possible. First implemented in the 1950s, turboshaft geometry has gone largely unchanged, but advances in materials and axial flow technology have continued to drive higher power and efficiency from today's turboshafts. Similarly to the turbojet and fan industry, there are only a handful of big players in the market. The usual suspects - Pratt & Whitney, General Electric, and Rolls-Royce - have taken over most of the industry, but lesser known companies like Lycoming and Turbomeca still hold a footing in the Turboshaft world. Nomenclature shp = Shaft Horsepower SFC = Specific Fuel Consumption FPT = Free Power Turbine HPT = High Power Turbine Introduction & Background Turboshaft engines are very similar to a turboprop engine; in fact many turboshaft engines were created by modifying existing turboprop engines to fit the needs of the rotorcraft they propel. The most common use of turboshaft engines is in scenarios where high power and reliability are required within a small envelope of requirements for size and weight. Most helicopter, marine, and auxiliary power units applications take advantage of turboshaft configurations. In fact, the turboshaft plays a workhorse role in the aviation industry as much as it is does for industrial power generation. While conventional turbine jet propulsion is achieved through thrust generated by a hot and fast exhaust stream, turboshaft engines creates shaft power that drives one or more rotors on the vehicle.
  • Gallery of USAF Weapons Note: Inventory Numbers Are Total Active Inventory figures As of Sept

    Gallery of USAF Weapons Note: Inventory Numbers Are Total Active Inventory figures As of Sept

    Gallery of USAF Weapons Note: Inventory numbers are total active inventory figures as of Sept. 30, 2014. By Aaron M. U. Church, Associate Editor I 2015 USAF Almanac BOMBER AIRCRAFT flight controls actuate trailing edge surfaces that combine aileron, elevator, and rudder functions. New EHF satcom and high-speed computer upgrade B-1 Lancer recently entered full production. Both are part of the Defensive Management Brief: A long-range bomber capable of penetrating enemy defenses and System-Modernization (DMS-M). Efforts are underway to develop a new VLF delivering the largest weapon load of any aircraft in the inventory. receiver for alternative comms. Weapons integration includes the improved COMMENTARY GBU-57 Massive Ordnance Penetrator and JASSM-ER and future weapons The B-1A was initially proposed as replacement for the B-52, and four pro- such as GBU-53 SDB II, GBU-56 Laser JDAM, JDAM-5000, and LRSO. Flex- totypes were developed and tested in 1970s before program cancellation in ible Strike Package mods will feed GPS data to the weapons bays to allow 1977. The program was revived in 1981 as B-1B. The vastly upgraded aircraft weapons to be guided before release, to thwart jamming. It also will move added 74,000 lb of usable payload, improved radar, and reduced radar cross stores management to a new integrated processor. Phase 2 will allow nuclear section, but cut maximum speed to Mach 1.2. The B-1B first saw combat in and conventional weapons to be carried simultaneously to increase flexibility. Iraq during Desert Fox in December 1998.
  • Comparison of Helicopter Engines

    Comparison of Helicopter Engines

    Comparison of Helicopter Engines John Schenderlein, Tyler Clayton Turboshafts...What are they? • Needed for high power in a small envelope • Very similar to turboprops • many turboshafts derived from turboprop engines • However, • exhaust is not used to propel • propeller load is applied to the airframe • Began ~1950s Main Uses • Helicopters • APUs • Marine Vehicles CH-53 Super Stallion • Tanks • Motorcycles • industrial power generation M1 Abrams MTT Superbike Major Players in the Market Turbomeca • French Manufacturer for small/medium turboshafts (500-3000 shp) • 18000+ in operation • Most popular engine: Arriel (600-1000 shp) • 30 variants • 245 lbs • SFC = 0.57 • 1 axial/1 Centrifugal compressor (PR ~9) • 2 HPT/1 FPT turbine Turbomeca • Newest Engine: Arrano (2018) • 10-15% increase SFC • new thermodynamic core & use of variable pitch inlet guide blades • Uses additive manufacturing for injectors Rolls-Royce • Most popular engine: M250 Series • inherited from Allison Engine Company (1990s) • 31000+ produced (50%+ in operation) • 450-715 shp • 160-275 lbs • 4-6 axial/1 centrifugal compressor (PR 6-9) • 2 HPT/2 FPT • Also used on the MTT Superbike RQ-8A Fire Scout Allison Engines (Rolls Royce) • Most noteable engine: T406 • Build specifically for the V-22 Osprey • 6150 shp • 971 lbs (6.33 p/w) • 14 axial compressor stages! Pratt and Whitney Canada • Canadian based subsidiary of PW • focuses on smaller aircraft engines • Majority of their engines based on the PT6 turboprop • PT6B/C series and the PT6T Twin-Pac (1000-2000 shp) • 3-4 axial/1
  • China's Pearl River Delta Escorted Tour

    China's Pearl River Delta Escorted Tour

    3rd - 13th October 2016 China’s Pearl River Delta Come and explore the amazing sites of China’s Pearl River Delta region on this tour that is the perfect blend Escorted Tour of historic and modern day China. Incorporating the destinations of Hong Kong, Guangzhou, Shenzhen, per person Twin Share Zhuhai and Macau you will experience incredible shopping, amazing scenery, historic sites and $4,995 ex BNE monuments, divine cuisine and possibly a win at the Single Supplement gaming tables! This is China like you have never $1,200 ex BNE seen it before!! BOOK YOUR TRAVEL INCLUSIONSINSURANCE WITH GO SEE Return EconomyTOURIN AirfaresG and Taxes ex Brisbane & RECEIVE A 25% 3 Nights in HongDISCOUNT Kong 3 Nights in Guangzhou 3 Nights in Macau 9 x Breakfasts 6 x lunches Book your Travel Insurance 7 x Dinners with Go See Touring All touring and entrance& fees receiv eas a 25% discount outlined in the itinerary China Entry Visa Gratuities for the driver and guide Train from Hong Kong to Guangzhou Turbojet Sea Express ferry from Macau to Hong Kong TERMS & CONDITIONS: * Prices are per person twin share in AUD. Single supplement applies. Deposit of $500.00 per person is required within 3 days of booking (unless by prior arrangement with Go See Touring), balance due by 03rd August 2016. For full terms & conditions refer to our website. Go See Touring Pty Ltd T/A Go See Touring Member of Helloworld QLD Lic No: 3198772 ABN: 72 122 522 276 1300 551 997 www.goseetouring.com Day 1 - Tuesday 04 October 2016 (L, D) Depart BNE 12:50AM Arrive HKG 7:35AM Welcome to Hong Kong!!!! After arrival enjoy a delicious Dim Sum lunch followed by an afternoon exploring the wonders of Kowloon.
  • 2. Afterburners

    2. Afterburners

    2. AFTERBURNERS 2.1 Introduction The simple gas turbine cycle can be designed to have good performance characteristics at a particular operating or design point. However, a particu­ lar engine does not have the capability of producing a good performance for large ranges of thrust, an inflexibility that can lead to problems when the flight program for a particular vehicle is considered. For example, many airplanes require a larger thrust during takeoff and acceleration than they do at a cruise condition. Thus, if the engine is sized for takeoff and has its design point at this condition, the engine will be too large at cruise. The vehicle performance will be penalized at cruise for the poor off-design point operation of the engine components and for the larger weight of the engine. Similar problems arise when supersonic cruise vehicles are considered. The afterburning gas turbine cycle was an early attempt to avoid some of these problems. Afterburners or augmentation devices were first added to aircraft gas turbine engines to increase their thrust during takeoff or brief periods of acceleration and supersonic flight. The devices make use of the fact that, in a gas turbine engine, the maximum gas temperature at the turbine inlet is limited by structural considerations to values less than half the adiabatic flame temperature at the stoichiometric fuel-air ratio. As a result, the gas leaving the turbine contains most of its original concentration of oxygen. This oxygen can be burned with additional fuel in a secondary combustion chamber located downstream of the turbine where temperature constraints are relaxed.