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Turbojet EngineApplied Thermodynamics
A jet engine having a turbine-driven compressor and developing thrust from the exhaust of hot gases is a turbojet engine.
This topic illustrates the working of a turbojet engine.
Turbojet Engine
Turbojet EngineApplied Thermodynamics
Thermodynamic Cycles
Two Isothermal processes and two adiabatic processes constitute a carnot cycle.
Two Adiabatic processes and two Constant pressure processes constitute a Brayton cycle.
Turbojet EngineApplied Thermodynamics
Brayton cycle is represented in P-v and T-s diagrams
Thermodynamic Cycles
Turbojet EngineApplied Thermodynamics
Working of a Turbojet Engine
In a turbojet engine, air enters axially into the rotor at state 1 and leaves the stator –rotor assembly in Axial direction at state 2.
Axial Flow Compressor (process 1-2)
Turbojet EngineApplied Thermodynamics
Working of a Turbojet Engine
• Then, air enters the combustion chamber in which fuel is mixed with air.
• High energy igniter supplies necessary spark at the starting of the cycle.
Combustion Chamber (process 2-3)
Turbojet EngineApplied Thermodynamics
Working of a Turbojet Engine
• The burnt Air fuel mixture is expanded in an Axial flow turbine.
• The work output of turbine is equal to work input of compressor.
• So, net work done by the Turbojet engine is Zero.
Axial Flow Turbine (process 3-4)
Turbojet EngineApplied Thermodynamics
Working of a Turbojet Engine
High pressure gases expand through nozzle which converts all pressure energy to Kinetic Energy.
Nozzle (process 4-5)
Turbojet EngineApplied Thermodynamics
Working of a Turbojet Engine
High Velocity jet of gases coming out of Nozzle gives the necessary thrust to move the engine forward. (Newton’s Third law of motion).
Pressure – Velocity variation in nozzle
Turbojet EngineApplied Thermodynamics
Resources
Books:
1. Gas Turbines by Cohen and Rogers
2. IC Engines and Gas Turbines by Gill Smith
Reference Links:
1. www.asme.org
Turbojet EngineApplied Thermodynamics
What is the difference between Rockets and jet engines?
Jet engines work on Newton’s III law of motion
Turbojet is an external combustion engine
Rockets operate at higher mach number than jet engines
Jet engines are self breathing engines
Turbojet EngineApplied Thermodynamics
Net Work Output of Turbojet engine is
Same as Compressor Work
Same as turbine Work
Zero
Equal to Wc- Wt
Turbojet EngineApplied Thermodynamics
Inlet temperature of air entering Turbojet depends on
Altitude of operation of flight
Monsoon conditions
Climatic conditions
It is always constant
Turbojet EngineApplied Thermodynamics
Where do we see the application of Turbojet engine?
Civil Aircrafts
Submarine
Helicopters
Rockets
Turbojet EngineApplied Thermodynamics
Answer Key
14
13
32
31
Answer(s)Question No.
