1. U3AEA04
ELEMENTS OF AERONAUTICS
Mr. SYED ALAY HASHIM
Assistant Professor
Department of Aeronautical Engineering
VEL TECH Dr. RR & Dr. SR TECHNICAL UNIVERSITY
Chennai
INDIA
12. Introduction
AEROSPACE ENGINES
• Comprehend the basic components of gas turbine
engines and their basic operations
• Comprehend the thermodynamic processes
occurring in a gas turbine engines
• Comprehend the support systems associated with
gas turbine engines
13. GAS TURBINE CYCLE
Single stage Ideal gas turbine cycle
Two stage turbine cycle
Gas Turbine Cycle
17. Compressor
• Supplies high pressure air for combustion process
• centrifugal flow and Axial flow
• Centrifugal Compressor
• Adv: simple design, good for low compression ratios (5:1), strong
• Disadvantage: Difficult to stage, less efficient, high frontal area
22. Classification of Engine
Jet Engines Reciprocating Engines
(Propulsive thrust is produced by jet)
Air Breathing Engine Non-Air Breathing Engine
(Using atm air to produced Power)
Engine
Gas Turbine Engine Non-Gas Turbine Engine
Turbojet Turboprop Turbofan Turbo-shaft
Ramjet Scramjet Pulsejet
(Presents of Fuel and absents of Air
instead of Air + Oxidizer. Hypersonic
vehicles, Operating Mach No : 15 to 20)
(Available moving parts like
Compressor and Turbine)
(No moving parts)
Rocket Engine
(No moving parts)
23.
24. Turbojet
Chemical energy is converted into mechanical energy
100% Thrust produced by Nozzle
Operating Mach No: 1 to 2
Supersonic Aircraft (1 to 5)
25.
26. Turbofan
20 to 40% of Thrust produced by Nozzle
60 to 80% of Thrust produced by Fan
Operating Mach No: 0.4 to 0.8
High Subsonic Aircraft (0.3 to 0.8)
27.
28. Turboprop
20 to 25% of Thrust produced by Nozzle
75 to 80% of Thrust produced by Propeller
Operating Mach No: 0.4 to 0.65
Subsonic Aircraft (0.1 to 0.8)
29. Turbo Shaft
High pressure turbine is used to
rotate HP & LP Compressor
Low pressure turbine is used to
rotate output Shaft
No Thrust produced in the exit
turbine gas
30. Turbo Shaft
Kinetic energy is converted to Shaft power
100% Thrust produced by Shaft
Operating Mach No: 0.4 to 0.8
High speed Subsonic helicopter (0.3 to 0.8)
31.
32. Pulse Jet
Made up of few moving parts
Valved engines use a mechanical valve to control the flow of expanding exhaust,
forcing the hot gas to go out the back of the engine through the tailpipe
Starting the engine usually requires forced air and an ignition method such as a
spark plug for the fuel-air mix.
It can operate statically
33. Rocket Engines
A rocket is a machine that develops thrust by the rapid expulsion of matter
A rocket is called a launch vehicle when it is used to launch a satellite or other
payload into space
Rocket engines are reaction engines
The highest exhaust velocities
It is used in missile
34. Passenger airplanes
Sl. No. Description Less Moderate High
1 Specific fuel consumption Turbofan Turboprop Turbojet
2 Noise Level Turbofan Turboprop Turbojet
3 Operating Mach No Turboprop Turbofan Turbojet
4 Take off Thrust Turbojet Turbofan Turboprop
5 Altitude Turboprop Turbofan Turbojet
6 Load Carrying capacity Turbojet Turboprop Turbofan
7 Specific Impulse Turbojet Turboprop Turbofan
35. Thrust Equation
Total Thrust = Momentum Thrust + Pressure Thrust
mi=mj (mass flow rate)
Inlet pressure = Exit pressure
Thrust force is the forward motion of engine
37. Methods of Thrust Augmentation
After burning
High thrust for short duration
It is used only in take-off (or) for high climbing rates
Additional fuel is burning in the tail pipe between the turbine and exhaust
nozzle
It is increased the jet velocity
Oxidizer-Fuel Mixture
Increase the mass flow rate
Evaporative cooling which produces higher pressure and higher mass flow rate
Increase the compressor pressure ratio due to reduced compressor air flow
Water and menthol or alcohol Mixture
41. Advantages of Gas turbine Engines
• Weight reduction of 70%
• Simplicity
• Reduced manning requirements
• Quicker response time
• Faster Acceleration/deceleration
• Modular replacement
• Less vibrations
• More economical
42. Disadvantages of Gas Turbine Engines
• Many parts under high stress
• High pitched noise
• Needs large quantities of air
• Large quantities of hot exhaust (target)
• Cannot be repaired in place