Representative Turbojet Engines

Prepared under
QIP-CD Cell Project
Lecture-13
Jet Propulsion
Ujjwal K Saha, Ph. D.
Department of Mechanical Engineering
Indian Institute of Technology Guwahati
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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
Number of Turbine Stages
Number of Combustors
17
3
10
Maximum Diameter
0.99 m
Maximum Length
5.28 m
Maximum Dry Weight
SFC at maximum power
Maximum Power
Compression Ratio at maximum RPM
1634 Kg
203.9 g/N/h
80,143 N
13.5:1
4
Engine Assembly
5
Engine Airflow
6
Compressor Assembly
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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
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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.
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Combustion Section
The Combustion chamber is and Can type Combustion chamber and
the parts are shown below.
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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.
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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.
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Applications of GE J79 Engines
B-58 Bomber
Lockheed Martin F-104
Mc Donnell Douglas F-4
F-16
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Teledyne CAE J69-T-25
Turbojet Engine
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Specifications
Number of compressor stages:
Number of turbine stages:
Number of combustors:
Maximum power at sea level:
SFC at maximum power:
Compressor ratio at max rpm:
Maximum diameter:
Maximum length:
Maximum dry weight:
1
1
1
4.559 kN
0.1162 kg/N/h
4:1
0.632 m
1.27 m
165 kg
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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
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C
U
T
A
W
A
Y
V
I
E
W
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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
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S
E
C
T
I
O
N
A
L
V
I
E
W
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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
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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
ÅCessna T-37A Tweet, Trainer aircraft USAF
Cessna T-37C, Trainer aircraft USAF Æ
Other application – target drones, special purpose aircraft
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References
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, 4th 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.
1.
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