440 likes | 857 Vues
Parametric Cycle Analysis of Ideal Turbo Jet Engine. P M V Subbarao Professor Mechanical Engineering Department Lecture - 8. Selection of Optimal Design Cruising Conditions…. Effect of Flight Mach Number on Compactness. r 0p =5. r 0p =3. r 0p =2. r 0p =1. r 0p =10. r 0p =20.
E N D
Parametric Cycle Analysis of Ideal Turbo Jet Engine P M V Subbarao Professor Mechanical Engineering Department Lecture - 8 Selection of Optimal Design Cruising Conditions….
Effect of Flight Mach Number on Compactness r0p=5 r0p=3 r0p=2 r0p=1 r0p=10 r0p=20 r0p=30 t0,cc=4.5 Specific Thrust kN.s/kg Mac
r0p Effect of Flight Mach Number on Fuel Air Ratio t0,cc=4.5 1 2 3 5 10 20 30 Mac
Effect of Flight Mach Number on Fuel Economy r0p=2 r0p=1 r0p=3 r0p=5 r0p=10 r0p=20 r0p=30 t0,cc=4.5 TSFC kg/ kN.hr Mac
r0p Effect of Flight Mach Number on Fuel Air Ratio t0,cc=4.5 1 2 3 5 10 20 30 Mac
Effect of Flight Mach Number on Propulsion Efficiency t0,cc=4.5 r0p= 30 r0p=2 r0p= 5 Mac
r0p Effect of Flight Mach Number on Thermal Efficiency t0,cc=4.5 Mac
Effect of Flight Mach Number on Overall Efficiency t0,cc=4.5 hO r0p Mac
Effect of Pressure Ratio on Compactness Mac=0 Mac=0.5 Mac=1.0 Mac=1.5 Mac=2.0 Mac=2.5 Mac=3.0 t0,cc=4.5 Specific Thrust kN.s/kg rp
Effect of Pressure Ratio on Fuel Economy t0,cc=4.5 Mac TSFC kg/ kN.hr rp
Effect of Pressure Ratio on Fuel Air Ratio t0,cc=4.5 rp
Effect of Pressure Ratio on Propulsive Efficiency t0,cc=4.5 rp
Effect of Pressure Ratio on Thermal Efficiency t0,cc=4.5 rp
Effect of Pressure Ratio on Overall Efficiency t0,cc=4.5 rp
Effect of Pressure Ratio on Compactness Mac=0 Mac=0.5 Mac=1.0 Mac=1.5 Mac=2.0 Mac=2.5 Mac=3.0 t0,cc=4.5 Specific Thrust kN.s/kg rp
inlet 1 2 7 5 6 3 4 Turbo Jet with Afterburner
Elevation of Temperature of the Jet: After Burner : More Energy at Same Life
Minimum Jet Temperature Jet Total Temperature : Jet Static Temperature :
Characterization of AB Jet Maximum obtainable Mach number of Jet
Performance of Jet Propulsive Power or Thrust Power: Specific Thrust S Thrust Specific Fuel Consumption TSFC
W AB W AB W/O AB W/O AB AB & No AB rp = 10 TSFC Specific Thrust
Ideal Afterburning Turbojet Engine Performance : Specific Thrust Vs Compressor Pressure Ratio 2.5 Specific Thrust kN.s/kg 3.0 rp
Ideal Turbojet Engine Performance : Specific Thrust Vs Compressor Pressure Ratio Maircraft Specific Thrust kN.s/kg Compressor Pressure Ratio : rp
Ideal Afterburning Turbojet Engine Performance : TSFC Vs Compressor Pressure Ratio TSFC kg/ kN.hr rp
Effect of Pressure Ratio on Fuel Economy Constant TIT TSFC kg/ kN.hr Mac rp
Ideal Afterburning Turbojet Engine Performance : TSFC Vs Compressor Pressure Ratio rp
Ideal Afterburning Turbojet Engine Performance : Efficiencies Vs Compressor Pressure Ratio rp
Summary of Turbojet Performance • A high compressor pressure ratio is desirable for subsonic flight for good specific thrust and low fuel consumption. • A special care must be used in selecting the compressor pressure ratio for the supersonic flight Mach number. • Rapid drop in specific thrust with pressure ratio at supersonic conditions. • There exist a pressure ratio for each Mach number of a supersonic flight, that gives maximum specific thrust. • The fuel air ratio decreases with increasing Mach number and compressor pressure ratio. • Propulsive efficiency increases with increasing Mach number. Rapid fall in specific thrust under supersonic conditions is a serious concern.
Optimization of Turbojet Performance P M V Subbarao Professor Mechanical Engineering Department Better Deal for Compactness & Fuel Economy…
Optimum Compressor Pressure Ratio • At supersonic flight conditions, a maximum value of Specific thrust is Exhibited at certain compressor pressure ratio. • The value of pressure ratio to maximize the specific thrust at a given flight Mach number should be found by differentiation of specific thrust equation. For Maximum Specific Thrust:
Optimum Compressor Pressure Ratio Vs Mach Number W AB r0p,opt W/o AB Mac
Optimal Turbojet Engine Performance With After Burner Specific Thrust kN.s/kg TSFC kg/ kN.hr Without After Burner Mac
Energy Flow in Jet Engine Energy input Long distance travel demands high flight velocity. High flight velocity leads to drop in compactness and fuel economy. A Single Jet is blackmailing the jet engine !!!