Question 5 State the definition of the propulsive efficiency and derive the below equation for propulsive efficiency np

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Question 5 State The Definition Of The Propulsive Efficiency And Derive The Below Equation For Propulsive Efficiency Np 1 (126.15 KiB) Viewed 45 times

Question 5 State the definition of the propulsive efficiency and derive the below equation for propulsive efficiency np = 2 Val (V; + Va) Where; Va- aircraft velocity and V; - jet velocity 5 marks When an aircraft engine is operate at the initial cruise condition, the outside temperature, pressure ratio and turbine entry temperature (TET) are 233K, 32, and 1250K respectively. Also the isentropic efficiencies of the compressor and turbine are 89% and 90% respectively. Consider for air y = 1.4, Cp = 1.005 KJ/kgk and for gas y = 1.3, Cp = 1.244 KJ/kgK Calculate the, (a) Net work, and 5 marks (b) Thermal efficiency. 5 marks Page 7 of 8 When the aircraft is cruising at 240 m/s, and assuming that the entire net work is used to increase the kinetic energy of the jet flow. (a) Find the jet velocity of the engine (b) Then calculate the () Propulsive efficiency and 5 marks (ii) Overall efficiency of the engine 5 marks (25 marks)