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# Jet engine ideal analysis

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A deck of slides that goes through a simple analysis of an Ideal Jet Engine

A deck of slides that goes through a simple analysis of an Ideal Jet Engine

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### Transcript

• 1. Jet Engine Ideal Analysis
• 2. Engine Efficiency • Propulsive Efficiency • Thermal Efficiency • Overall Efficiency
• 3. Propulsive Efficiency • The propulsive efficiency compares how much work is done on the aircraft, by supplying kinetic energy to the air.
• 4. Propulsive Efficiency Va m=100kg/s Compressor =10 Exhaust Combustor Turbine =10 Combustor m=100kg/s VJ
• 5. Thermal Efficiency • The thermal 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 • The overall Efficiency compares the work done on the aircraft to the energy given by the fuel.
• 7. Arrangement of Engine T1=288 K 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=1112 K Combustor Turbine =10 Combustor Exhaust
• 9. Compressor T1=288 K P1=101kPa m=100kg/s T2=556 K P2=1010kPa Compressor =10 T3=1112 K Combustor Turbine =10 Combustor Wc Exhaust
• 10. Turbine T1=288 K P1=101kPa m=100kg/s T3=1112 K P3=1010kPa T2=556 K 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=556 K 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=1112 K 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=556 K 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=556 K 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’=556 K 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=1112 K 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’=556 K 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’=556 K 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’=556 K 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’=556 K 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’=556 K 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’=556 K 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’=556 K 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’=556 K 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 3 T3=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 3 T3=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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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 when we install an afterburner?
• 39. T1=288 K P1=101kPa m=100kg/s Afterburner T3=1112 K P3=1010kPa T2’=556 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=1112 K 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=603 K 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 Afterburner and Jet Engine With only the Engine