Lecture-13 Prepared under QIP-CD Cell Project Jet Propulsion Ujjwal K Saha, Ph. D. Department of Mechanical Engineering Indian Institute of Technology Guwahati 1
GE J79 Turbojet 2
Features Highly used engine for Military aircrafts specially in Supersonic Fighters. Developed in early 1955 during the initial cold war period by General Electric for McDonnell Douglas, Lockheed Martin and North American. 3
Specifications Number of Compressor Stages 17 Number of Turbine Stages 3 Number of Combustors 10 Maximum Diameter Maximum Length Maximum Dry Weight SFC at maximum power Maximum Power 0.99 m 5.28 m 1634 Kg 203.9 g/n/h 80,143 N Compression Ratio at maximum RPM 13.5:1 4
Engine Assembly 5
Engine Airflow 6
Compressor Assembly 7
Compressor Assembly 1. Compressor Front Frame : The Compressor Front Frame forms the air inlet passage for the engine and supports the front of the compressor rotor. Frame is made of Stainless Steel and has eight evenly placed hollow struts and also 20 inlet guide vanes for the first compressor stage. 2. Compressor Casing Assembly : Compressor casing Assemblies consist of two cylindrical, stainless steel casing, split along the horizontal line for removal. 8
Compressor Assembly 3. Compressor Rotor : The Compressor rotor consists of a front stub shaft, 17 disks, spacers and sets of blades as shown below 9
Compressor Assembly 4. Compressor Rear Frame : The compressor rear frame absorbs the thrust loading of the rotors and radial forces of the compressor turbine coupling. 10
Combustion Section The Combustion chamber is and Can type Combustion chamber and the parts are shown below. 11
Turbine Assembly 12
Turbine Assembly Turbine Stator Assembly : The turbine stator assembly is split on a horizontal line for easy removal and includes the second and third stage nozzles assembled into the turbine casing. Turbine Rotor: The turbine rotor provides the rotary power to the compressor. The rotor is equipped with three sets of rotor blades and two torque rings. It also consists of the hollow conical shaft. The shaft has an external spline that engages with the compressor rotor rear stub shaft. 13
Afterburner Assembly 14
Afterburner Assembly Forward Exhaust Duct Assembly : The forward exhaust is bolted to the rear flange of the turbine frame. After Burner Manifold and Multijet Fuel Nozzle : The four after burner manifolds encircles the forward exhaust duct. Each manifold has 21 outlets ports. Holes in the side of the tubes spray the fuel at right angles to the exhaust flow. Pilot Burner : The pilot burner, or the torch igniter, ignite the afterburner fuel in the exhaust section. The pilot burner attaches to the forward exhaust duct at the bottom and extends into the innner and the middle flame holder. Flame Holder : The flame holder consists of three concentric, V gutter rings connected by seven, equally spaced radial links. The rings are staggered to ensure efficient burning. 15
Tailpipe Assembly The tailpipe assembly consists of rear exhaust duct, liners and the exhaust nozzle. The liners are ceramic coated to withstand high after the high after burner temperature. The exhaust nozzle assembly consists of 24 flaps and seals interconnected by flap actuators and bellcranks to provide variable opening area of the exhaust nozzle. 16
Applications of GE J79 Engines B-58 Bomber Mc Donnell Douglas F-4 Lockheed Martin F-104 F-16 17
Teledyne CAE J69-T-25 Turbojet Engine 18
Specifications Number of compressor stages: 1 Number of turbine stages: 1 Number of combustors: 1 Maximum power at sea level: 4.559 kn SFC at maximum power: 0.1162 kg/n/h Compressor ratio at max rpm: 4:1 Maximum diameter: 0.632 m Maximum length: 1.27 m Maximum dry weight: 165 kg 19
Specifications cont J69 engine consists of Accessory case Compressor housing Turbine housing External accessories Starter generator (airframe supplied) Starting-fuel system Ignition system Fuel pump Fuel control Oil pump Oil filter Fuel, air and oil lines 20
C U T A W A Y V I E W 21
Construction Centrifugal compressor blades integral with hub metal Turbine blade removable & replaceable Combustion chamber (side-entry annular, L shaped) sheet-metal construction of high-temp.-resistant alloy Turbine-shaft-assembly part machined Turbine housing, turbine inlet nozzle, radial and exhaust diffuser welded, build up construction Compressor housing, accessory case, its cover, oil pump, drive adaptor, starter-generator adaptor, axial diffuser, rear bearing housing, front bearing cage etc. machined item 22
S E C T I O N A L V I E W 23
Air flow Primary air (Part B & Part C) Forms air-fuel mixture in cc Part C cools the vanes of turbine inlet nozzle Secondary air (Part D) Dilute the combustion product and hence holds down peak temperatures 24
Operation, some statistics Flame established 3500 rpm Starter-generator cutout 5000 rpm Starting combustion occurs 1500 to 2000 rpm 25
Continental J69-T-25, Application Cessna T-37A Tweet, Trainer aircraft USAF Cessna T-37C, Trainer aircraft USAF Other application target drones, special purpose aircraft 26
References 1. Hill, P.G., and Peterson, C.R., (1992), Mechanics and Thermodynamics of Propulsion, Addison Wesley. 2. Saravanamuttoo, H.I.H, Rogers, G.F.C, and. Cohen, H, (2001), Gas Turbine Theory, Pearson Education. 3. Oates, G.C., (1988), Aerothermodynamics of Gas Turbine and Rocket Propulsion, AIAA, New York. 4. Mattingly, J.D., (1996), Elements of Gas Turbine Propulsion, McGraw Hill. 5. Cumpsty, N.A., (2000), Jet Propulsion, Cambridge University Press. 6. Bathie, W.W., (1996), Fundamentals of Gas Turbines, John Wiley. 7. Treager, I.E., (1997), Aircraft Gas Turbine Engine Technology, Tata McGraw Hill. 8. Anderson, J. D. Jr., (2000), Introduction to Flight, 4 th Edition, McGraw Hill. 9. M.J.L.Turner, (2000), Rocket and Spacecraft Propulsion, Springer. 10. Sutton, G.P. and Biblarz, O., (2001), Rocket Propulsion Elements, John Wiley & Sons. 11. Zucrow, M.J., (1958), Aircraft and Missile Propulsion, Vol. II, John Wiley. 12. Barrere, M., Jaumotte, A., Veubeke, B., and Vandenkerckhove, J., (1960), Rocket Propulsion, Elsevier. 27
Web Resources 1. http://www.soton.ac.uk/~genesis 2. http://www.howstuffworks.co 3. http://www.pwc.ca/ 4. http://rolls-royce.com 5. http://www.ge.com/aircraftengines/ 6. http://www.ae.gatech.edu 7. http://www.ueet.nasa.gov/engines101.html 8. http://www.aero.hq.nasa.gov/edu/index.html 9. http://home.swipnet.se/~w65189/transport_aircraft 10. http://howthingswork.virginia.edu/ 11. http://www2.janes.com/ww/www_results.jsp 12. http://www.allison.com/ 13. http://wings.ucdavis.edu/book/propulsion 14. http://www.pilotfriend.com/ 15. http://www.aerospaceweb.org/design/aerospike 16. http://www.grc.nasa.gov 17. http://www.hq.nasa.gov/office/pao/history 18. http://membres.lycos.fr/bailliez/aerospace/engine 19. http://people.bath.ac.uk/en2jyhs/types.htm 20. http://roger.ecn.purdue.edu/~propulsi/propulsion/rockets 21. http://www.waynesthisandthat.com/ep2.htm 22. http://www.answers.com/main 23. http://www.astronautix.com 28