Jet engine Cycles for Aircraft propulsion Notes | EduRev

: Jet engine Cycles for Aircraft propulsion Notes | EduRev

 Page 1


1
Lect-7
Page 2


1
Lect-7
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
2
Lect-7
In this lecture...
• Jet engine cycles for aircraft propulsion
– Turbojet engine
– Turbojet engine with afterburning
– Turbofan and its variants
– Turboprop and turboshaft engines
– Ramjet engines
Page 3


1
Lect-7
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
2
Lect-7
In this lecture...
• Jet engine cycles for aircraft propulsion
– Turbojet engine
– Turbojet engine with afterburning
– Turbofan and its variants
– Turboprop and turboshaft engines
– Ramjet engines
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
3
Lect-7
Gas Turbine Cycles
• Gas turbine engines operate on Brayton
cycles.
• Ideal Brayton cycle is a closed cycle, 
whereas gas turbines operate in the open 
cycle mode.
• Ideal cycle assumes that there are no 
irreversibilities in the processes, air 
behaves like an ideal gas with constant 
specific heats, and that there are no 
frictional losses.
Page 4


1
Lect-7
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
2
Lect-7
In this lecture...
• Jet engine cycles for aircraft propulsion
– Turbojet engine
– Turbojet engine with afterburning
– Turbofan and its variants
– Turboprop and turboshaft engines
– Ramjet engines
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
3
Lect-7
Gas Turbine Cycles
• Gas turbine engines operate on Brayton
cycles.
• Ideal Brayton cycle is a closed cycle, 
whereas gas turbines operate in the open 
cycle mode.
• Ideal cycle assumes that there are no 
irreversibilities in the processes, air 
behaves like an ideal gas with constant 
specific heats, and that there are no 
frictional losses.
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
4
Lect-7
Ideal cycle for jet engines
• All air-breathing jet engines operate on the 
Brayton cycle (open cycle mode).
• The most basic form of a jet engine is a 
turbojet engine. 
• Some of the parameters of a jet engine 
cycle are usually design parameters and 
hence often fixed a priori: eg. compressor 
pressure ratio, turbine inlet temperature etc.
• Cycle analysis involves determining the 
performance parameters of the cycle with 
the known design parameters.
Page 5


1
Lect-7
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
2
Lect-7
In this lecture...
• Jet engine cycles for aircraft propulsion
– Turbojet engine
– Turbojet engine with afterburning
– Turbofan and its variants
– Turboprop and turboshaft engines
– Ramjet engines
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
3
Lect-7
Gas Turbine Cycles
• Gas turbine engines operate on Brayton
cycles.
• Ideal Brayton cycle is a closed cycle, 
whereas gas turbines operate in the open 
cycle mode.
• Ideal cycle assumes that there are no 
irreversibilities in the processes, air 
behaves like an ideal gas with constant 
specific heats, and that there are no 
frictional losses.
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
4
Lect-7
Ideal cycle for jet engines
• All air-breathing jet engines operate on the 
Brayton cycle (open cycle mode).
• The most basic form of a jet engine is a 
turbojet engine. 
• Some of the parameters of a jet engine 
cycle are usually design parameters and 
hence often fixed a priori: eg. compressor 
pressure ratio, turbine inlet temperature etc.
• Cycle analysis involves determining the 
performance parameters of the cycle with 
the known design parameters.
Prof. Bhaskar Roy, Prof. A M Pradeep, Department of Aerospace, IIT Bombay
5
Lect-7
Ideal cycle for jet engines
a 1 2 3 4 5 6 7
Compressor
Diffuser
Combustion chamber/burner
Turbine
Afterburner
Nozzle
Schematic of a turbojet engine and 
station numbering scheme
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