This so called PPT for propulsion study for Shenyang Aerospace University. This PPT right protected by Dr. divinder K. Yadav. Its using in SAU by Lale. For all students of Aeronautical Engineering must memorize each & every words from this PPT. If you miss a single words you must fail in the Exam. Remember there is no chance to be creative or use sense you just need to use the power of memorizing.

1. 1© Devinder K Yadav

2. Thrust Reversers
2

3. Turbojet/turbofan Thrust Reversers
Aid in braking and directional control
during normal landings and Rejected
Take-Offs (RTOs)
Allow some aircraft to back out using
their own power
Reduce brake maintenance
3

4. Turbojet/turbofan Thrust Reversers
There are two types of thrust reverser used
• Cascade reversers (Aerodynamic Blockage)
• Clamshell reversers (Mechanical Blockage)
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5. 5

6. Thrust Reversers
Clamshell reversers (Mechanical Blockage)
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7. Thrust Reversers
Cascade reversers (Aerodynamic Blockage)
7

8. Turbojet/turbofan Thrust Reversers
Clamshell reverser
8

9. Clamshell Thrust Reverser
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10. Clamshell Thrust Reverser
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11. Turbojet/turbofan Thrust Reversers
Cascade Reverser
11

12. Cascade type
Thrust
Reversers
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13. Cascade Thrust Reverser
13

14. Cascade Thrust Reverser
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15. Turbofan Thrust Reversers
Cascade & clamshell reverser
Cold stream reverser
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16. Turbojet/turbofan Thrust Reversers
Reversers are angled forward enough to
give reverse thrust but not enough to
allow re-ingestion of exhaust gases
Reverse thrust is usually limited to speeds
above 60-70 knots to minimise foreign
object damage (FOD) ingestion
16

17. Turbojet/turbofan Thrust Reversers
To prevent reverse thrust
being accidentally engaged
while under forward power
interlocks allow thrust
reverser lever movement only
when the thrust level is at
idle.
Maintenance on thrust
reverser systems is high and
modern carbon brakes and
auto wheel braking systems
are minimising the use of
thrust reversers 17

18. Turbojet/turbofan Thrust Reversers
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19. 19

20. 20

21. Thrust Reversers Safety Features
(Full Authority Digital Electronic Control)
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22. Noise Suppression
Sources of Noise
• Intake Duct (acoustic panels installed in nose cowl to suppress this noise)
• Engine Housing
• Fan
• Compressor
• Exhaust Duct (Small eddies near the exhaust duct cause high frequency
noise and downstream larger eddies create low frequency noise).
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23. Noise Suppression
Exhaust duct noise
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24. Noise Suppression
Exhaust duct noise
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25. Noise Suppression
Exhaust duct noise
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26. Noise Suppression
Exhaust duct noise
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27. Noise Suppression
Exhaust duct noise
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28. Noise Suppression
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29. Noise Suppression Devices
• Corrugated Perimeter noise suppressor
• Multi-tube type noise suppressor.
Both types of suppressors break up the single, main
jet exhaust stream into a number of smaller jet
streams. This increases the total perimeter of the
nozzle area and reduces the size of the eddies created
as the gases are discharged into the open air.
Although the total noise energy remains unchanged,
the frequency is raised considerably.
29

30. Noise Suppression Devices
Corrugated Perimeter type Multi-tube type
30

31. Noise Suppression Devices
31

32. Noise Suppression Devices
32

33. Noise Suppression Devices
Noise absorbing lining material converts
acoustic energy into heat energy.
The liner material is matched to the
character of the noise for optimum
suppression.
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34. Noise
Suppression
Devices
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35. Thrust Augmentation
Water Injection System
35

36. Water Injection
Because thrust is proportional to:
Mass × Acceleration
it is affected by changes in the mass of air
passing through the engine.
Typically hot temperatures at a high
altitude aerodrome will mean reduced air
mass.
36

37. Water Injection
The principle of latent heat of vaporisation
applies to the water injection process.
Water is injected into the compressor inlet
or the diffuser (sometimes both).
As the water evaporates it cools the air
around it.
37

38. Water Injection
The heat transfer will reduce the
temperature of the air mass making the gas
flow more dense and increasing mass air
flow.
As the mass air flow increases it allows
more fuel to be used without exceeding
turbine temperature limits.
38

39. Water Injection (System Operation
39

40. Water Injection (System Operation)
40

41. Water
Injection
System
41

42. Water Injection System
42

43. The water must be pure de-mineralised to
minimise the deposit of solids on turbine blades.
Methanol is added to act as an anti-freeze by
lowering the freezing point of the water.
A water methanol fluid means a single uplift can
be used for consecutive take-offs without
damage due to freezing.
Water Injection (System Operation
43

44. Water injection typically increases
thrust by 30%.
Care must be taken not to over-boost
the engine when switching water
injection on.
Water Injection (System Operation
44

45. Turbojet thrust restoration Turboprop power boost
45

46. Afterburners
• More fuel added to exhaust and ignited
• Lots more thrust but very fuel inefficient
• Greater requirement for variable area exhaust
nozzle
On SST Concord; Afterburner used to take-off and accelerate from Mach 0.93
to Mach 1.7
46

47. Afterburners
47

48. Afterburners
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49. Afterburners
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50. Afterburners
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51. Afterburners
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52. Afterburners
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53. 1© Devinder K Yadav

54. Turboprop Operation
Turboprops (and turboshafts) recover
energy from the hot gas stream and
convert it to mechanical energy
There are two types of powerplants
fixed shaft turbine
free shaft turbine
2

55. 3

56. Turboprop Operation
Advantages of fixed turbine
Operate at a constant RPM (adding fuel
changes propeller pitch) so can optimise
internal aerodynamics
More immediate power response
More fuel efficient
Lighter
4

57. Turboprop Operation
Advantages of free turbine
Low noise at ground idle
Easier engine start
Propeller can be stopped while the engine is
still operating
Propeller/gearbox vibrations aren’t
transmitted to the gas generator
Easy to disassemble for service
5

58. Free Turbine
6

59. Fixed Turbine
7

60. Turboprop Operation
Both fixed and free turbines require a
speed reduction gearbox between the
turbine and the propeller
The gearbox converts low torque high
RPM to high torque low RPM
8

61. Turboprop operation
9

62. 10

63. SAAB 2000 Flight Deck
11

64. Turboprop Operation
Negative torque protection
An NTS is incorporated to reduce
windmilling drag and stop the propeller
driving the engine
A gas turbine compressor absorbs a large
amount of energy increasing propeller
drag of a windmilling propeller
12

65. Turboprop Operation
NTS won’t feather the propeller
NTSing will occur until the pilot feathers
the propeller
NTS Lockout necessary to stop NTS occurring
on landing
13

66. Beta Control
Turboprop operations can be broken into
two ranges of operation
Ground (range) operations
Flight (range) operations
A gate in the power lever operating range
separates the two ranges of operation
14

67. 15

68. Turboprop operations
Operations in ground range is known as
the Beta range
In flight range the propeller governor
controls the speed of the propeller
In Beta (ground) range the fuel control unit
automatically controls the engine RPM at a
preset value and movement of the power
lever controls blade angle
16

69. http://www.grc.nasa.gov/WWW/K-12/airplane/ngnsim.html
NASA engine simulator –
try it, you’ll like it
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