Parametric Study of Turbofan Performance P M V

Parametric Study of Turbofan Performance P M V Subbarao Professor Mechanical Engineering Department Identification of Sensitive Design & Operationa Variables ……

Performance of An Ideal Turbofan Inlet

Performance Analysis of Turbofan • Performance Parameters: Specific Thrust & TSFC • Operational Parameters : Flight Mach number & Ambient conditions. • Design Variables : Fan Pressure Ratio, Bypass Ratio, Compressor Pressure Ratio, Combustion Chamber Temperature Ratio. • Fan Effects : • Fan Pressure Ratio • Bypass Ratio. • Fan Stream Thrust Vs Total Thrust.

Influence of Fan: Pressure Ratio: Mac = 0. 75 r 0, p, comp=15. 0 a=4. 0 T 0 max=1200 K

Combined Effect of Fan & Compressor Pressure Ratios a=4. 0 T 0 max=1200 K Mac =0. 75

Combined Effect of Fan & Compressor Pressure Ratios a=4. 0 TSFC T 0 max=1200 K Mac =0. 75

Optimum Fan Pressure Ratio for Fuel Economy TSFC r 0, p, comp=24 T 0 max=1800 K Mac =0. 9 =5 12 10 8 7 =3 =4 =6 Fan Pressure Ratio

Optimum Fan Pressure Ratio for Compactness Specific Thrust k. N. s/kg =3 =4 =5 6 8 7 10 12 r 0, p, comp=24 T 0 max=1800 K Mac =0. 9 Fan Pressure Ratio

Optimum Fan Pressure Ratio for Propulsion Efficiency r 0 p, comp=24 T 0 max=1800 K Mac =0. 9 Fan Pressure Ratio

Combined Effect of Fan & Compressor Pressure Ratios a=4. 0 Specific Thrust k. N. s/kg Fan Pressure Ratio r 0 p, fan=3. 5 T 0 max=1200 K Mac =0. 75 r 0 p, fan=3. 0 r 0 p, fan=4. 5 r 0 p, fan=2. 0 r 0 p, fan=1. 5 Compressor Pressure Ratio

Combined Effect of Fan & Compressor Pressure Ratios a=4. 0 T 0 max=1200 K Mac =0. 75 TSFC Fan Pressure Ratio Compressor Pressure Ratio

Fan Effects on Fuel Economy: r 0, p, fan=2. 5 & Mac=0. 75 =1. 5 =0. 5 =1. 0 TSFC =2 =3 =5 =8 =12 Compressor Pressure Ratio =4

Optimization Analysis of Turbofan • Operational Parameters : Flight Mach number & Ambient conditions. • Design Variables : Fan Pressure Ratio, Bypass Ratio, Compressor Pressure Ratio, Combustion Chamber Temperature Ratio. • Maximization of specific thrust is not an important issue. • Fuel economy is the main focus for optimization.

Thrust Specific Fuel Consumption TSFC Neglect the value of f in denominator, as the value of f is <<1

Simplified Model for TSFC For maximum fuel economy, maximize the denominator.

Simplified Objective Function Core Effects : Bypass Ratio, Compressor Pressure Ratio & Combustion Chamber Temperature Ratio. Fan Effects : Fan Pressure Ratio & Bypass Ratio.

Selection of Optimum Bypass Ratio As fan handles the entire air intake, Vcoldjet is independent of bypass ratio

Modified Objective Function Rewrite OF for best as:

Relative change in Turbine TR to BPR

The final Objective function for best