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Jet engine ideal analysis
The document analyzes the ideal performance of a jet engine through three parts. It examines the propulsive, thermal, and overall efficiencies. The compressor compresses the air 10 times while the turbine expands it 10 times. With compressor and turbine efficiencies of 85%, the useful work is 14,100kJ. The combustion temperature is 1112K and heat supplied is 50,900kJ. The nozzle exhaust is choked with pressure of 129kPa and temperature of 664K. Specific fuel consumption is calculated based on the heat required to increase the air temperature. An afterburner is considered which further increases the exhaust temperature.
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Jet engine ideal analysis
- 1. Jet Engine IdealAnalysis
- 2. Engine Efficiency • PropulsiveEfficiency • Thermal Efficiency • Overall Efficiency
- 3. Propulsive Efficiency • Thepropulsive efficiency compares how much work is done on the aircraft, by supplying kinetic energy to the air.
- 4.
- 5. Thermal Efficiency • Thethermal efficiency of an engine is the efficiency of the conversion of the heat energy released by the fuel into kinetic energy in the jet stream.
- 6. Overall Efficiency • Theoverall Efficiency compares the work done on the aircraft to the energy given by the fuel.
- 7. Arrangement of Engine T1=288K P1=101kPa m=100kg/s T3=1112 K Compressor =10 Combustor Turbine =10 Exhaust Combustor Turbine Entry Temperature 1112°K Compressor compression ratio = Turbine expansion ratio. 10 Specific Heat Capacity of Air at constant Pressure (Cp) Ratio of Specific Heat Capacities for air ( ) Universal Gas Constant (R) 1 kJ/kg °K 1.4 287 kJ/kg °K Inlet Air Temperature 288°K Outside air pressure 101 kPa Mass flow of air 100kg/s Calorific value of fuel is 43,000 kJ/kg
- 8. Compressor T1=288 K P1=101kPa m=100kg/s T2=556 K P2=1010kPa Compressor =10 T3=1112K Combustor Turbine =10 Combustor Exhaust
- 9. Compressor T1=288 K P1=101kPa m=100kg/s T2=556 K P2=1010kPa Compressor =10 T3=1112K Combustor Turbine =10 Combustor Wc Exhaust
- 10. Turbine T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2=556K P2=1010kPa Compressor =10 T4=576 K P4=101kA Combustor Turbine =10 Combustor Exhaust
- 11. Turbine T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2=556K P2=1010kPa Compressor =10 T4=576 K P4=101kA Combustor Turbine =10 Exhaust Combustor WT
- 12. Useful Work T1=288 K P1=101kPa m=100kg/s T3=1112K P3=1010kPa T2=556 K P2=1010kPa Compressor =10 T4=576 K P4=101kA Combustor Turbine =10 26,800kJ Combustor Exhaust Subtract the Work done by the compressor (WC)from the work done on the turbine (WT) to determine the useful work done by the engine on the aircraft. Useful Work = WT – WC. Useful Work = (53,600-26,800)=26,800 kJ
- 13. Combustor T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2=556K P2=1010kPa Compressor =10 T4=576 K P4=101kA Combustor Turbine =10 Combustor Q Exhaust
- 14. Fuel T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2=556K P2=1010kPa Compressor =10 T4=576 K P4=101kA Combustor Turbine =10 Combustor Q Exhaust
- 15. Efficiency T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K P2=1010kPa Compressor =10 T4’=576 K P4=101kA Combustor Turbine =10 Combustor Q Exhaust
- 16. Part 2 T1=288 K P1=101kPa m=100kg/s T3=1112K P3=1010kPa T2’=556 K P2=1010kPa Compressor =10 T4’=576 K P4=101kA Combustor Turbine =10 Combustor Q Repeat the analysis but with the compressor and turbine efficiencies at 85%. Exhaust
- 17. Compressor T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 T4’=576 K P4=101kA Combustor Turbine =10 Combustor Q Exhaust
- 18. Compressor T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 T4’=576 K P4=101kA Combustor Turbine =10 Combustor Q Exhaust
- 19. Turbine T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 T4’=576 K T4 = 656 K P4=101kA Combustor Turbine =10 Combustor Q Exhaust
- 20. Turbine T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 T4’=576 K T4 = 656 K P4=101kA Combustor Turbine =10 Combustor Q Exhaust
- 21. Turbine T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 T4’=576 K T4 = 656 K P4=101kA Combustor Turbine =10 14,100kJ Combustor Exhaust Q Subtract the Work done by the compressor (WC)from the work done on the turbine (WT) to determine the useful work done by the engine on the aircraft. Useful Work = WT – WC. Useful Work = (45,600-31,500)=14,100 kJ
- 22. Combustor T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 T4’=576 K T4 = 656 K P4=101kA Combustor Turbine =10 14,100kJ Combustor Exhaust Q=50900kJ
- 23. Combustor T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 T4’=576 K T4 = 656 K P4=101kA Combustor Turbine =10 14,100kJ Combustor Exhaust Q=50900kJ
- 24. Efficiency T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 Combustor Turbine =10 T4’=576 K T4 = 656 K P4=101kA 14,100kJ Combustor Exhaust Q=50900kJ
- 25. T1=288 K P1=101kPa m=100kg/s Part 3T3=1112 K P3=1010kPa T2’=556 K T2=603 K P2=1010kPa Compressor =10 Combustor Turbine =10 T4’=576 K T4 = ? K P4=?kA 14,100kJ Combustor Q=50900kJ Therefore the work done by the turbine is also 31,500kJ
- 26. T1=288 K P1=101kPa m=100kg/s Part 3T3=1112 K P3=1010kPa T2’=556 K T2=603 K P2=1010kPa Compressor =10 Combustor Combustor Q=50900kJ Turbine =10 T4’=576 K T4 = 797 K P4=?kA Nozzle
- 27. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Combustor Turbine =10 T4’=741 K T4 = 797 K P4=?kA Nozzle
- 28. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kPa Nozzle
- 29. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kA Nozzle P5
- 30. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kA Nozzle Combustor P5=129kPa As P5 is > P1 the nozzle is choked.
- 31. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kA Nozzle Combustor P5=129kPa
- 32. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kA Nozzle Combustor P5=129kPa
- 33. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kA Nozzle Combustor P5=129kPa T5=664K
- 34. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kA Nozzle Combustor P5=129kPa T5=664K
- 35. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kA Nozzle Combustor P5=129kPa T5=664K
- 36. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kA Nozzle Combustor P5=129kPa T5=664K Calculate the Specific Fuel Consumption of the engine. The burning of the fuel heats the air from T2 to T3 Heat Energy required is: Q=m.cp(T3- T2 ) Q = 100 (1)(1112-603) = 50871kJ
- 37. T1=288 K P1=101kPa m=100kg/s Part 3 T3=1112K T2’=556 K P3=1010kPa T2=603 K P2=1010kPa Q=50900kJ Compressor =10 Combustor Turbine =10 T4’=741 K T4 = 797 K P4=244kPa Nozzle Combustor P5=129kPa T5=664K
- 38. What happens whenwe install an afterburner?
- 39. T1=288 K P1=101kPa m=100kg/s Afterburner T3=1112 K P3=1010kPa T2’=556K T2=603 K P2=1010kPa Compressor =10 Combustor T4’=576 K T4 = 797 K P4=244kPa Turbine =10 T5 = ? K P5=? Afterburner Combustor Q=50900kJ The exhaust gas is reheated to 2000K. the calculations are the same as that the dry turbojet, but now the nozzle inlet temperature is 2000K. Nozzle
- 40. m=100kg/s T2’=556 K T2=603 K P2=1010kPa Compressor =10 T3=1112K P3=1010kPa Q=50900kJ Combustor Combustor Turbine =10 T4’=576 K T4 = 797 K P4=244kPa T5 = ? K P5=129kPa Afterburner Nozzle T1=288 K P1=101kPa Afterburner
- 41. m=100kg/s T2’=556 K T2=603 K P2=1010kPa Compressor =10 T3=1112K P3=1010kPa Q=50900kJ Combustor Combustor Turbine =10 T4’=576 K T4 = 797 K P4=244kPa T5 = 1667 K P5=129kPa Afterburner Nozzle T1=288 K P1=101kPa Afterburner
- 42. m=100kg/s T2’=556 K T2=603 K P2=1010kPa Compressor =10 T3=1112K P3=1010kPa Q=50900kJ Combustor T4’=576 K T4 = 797 K P4=244kPa Turbine =10 Combustor At the throat of the nozzle, the air is travelling at the speed of sound. Determine the velocity of the jet. T5 = 1667 K P5=129kPa Afterburner Nozzle T1=288 K P1=101kPa Afterburner
- 43. m=100kg/s T2’=556 K T2=603 K P2=1010kPa Compressor =10 T3=1112K P3=1010kPa Q=50900kJ Combustor Combustor Turbine =10 T4’=576 K T4 = 797 K P4=244kPa T5 = 1667 K P5=129kPa Afterburner Nozzle T1=288 K P1=101kPa Afterburner
- 44. m=100kg/s T2’=556 K T2=603 K P2=1010kPa Compressor =10 T3=1112K P3=1010kPa Q=50900kJ Combustor Combustor Turbine =10 T4’=576 K T4 = 797 K P4=244kPa T5 = 1667 K P5=129kPa Afterburner Nozzle T1=288 K P1=101kPa Afterburner
- 45. m=100kg/s T2’=556 K T2=603 K P2=1010kPa Compressor =10 T3=1112K P3=1010kPa Q=50900kJ Combustor Combustor Turbine =10 T4’=576 K T4 = 797 K P4=244kPa T5 = 1667 K P5=129kPa Afterburner Nozzle T1=288 K P1=101kPa Afterburner
- 46. m=100kg/s T2’=556 K T2=603 K P2=1010kPa Compressor =10 T3=1112K P3=1010kPa Q=50900kJ Combustor Combustor Turbine =10 T4’=576 K T4 = 797 K P4=244kPa T5 = 1667 K P5=129kPa Afterburner Nozzle T1=288 K P1=101kPa Afterburner
- 47. m=100kg/s T3=1112 K P3=1010kPa T2’=556 K T2=603K P2=1010kPa Compressor =10 Combustor Turbine =10 T4’=576 K T4 = 797 K P4=244kPa T5 = 1667 K P5=129kPa Afterburner Combustor Q=50900kJ m=1.18kg Q=120300kJ M=2.797kg Nozzle T1=288 K P1=101kPa Afterburner
- 48. Comparison between Afterburnerand Jet Engine With only the Engine