The air entering compressor of turbojet at 320 degree K the

The air entering compressor of turbojet at 320 degree K. the compressor total pressure ratio = 15. the heating value of the fuel = 41,400 kj/kg and fuel mass flow rate = 1.26 kg/s. the total pressure at combustor inlet = 2200 kpa. Assume nozzle outlet static pressure = pa = 101 kpa and sound speed at nozzle outlet = 475 m/s. if the air mass flow rate = 80 kg/s and jet engine speed = 275 m/s, what will be the thrust force of the engine? use k for air = 1.4 and CP_a = 1.005 kj/kg. assume ideal work exchange between engine turbine and compressor.

Solution

mass of air flow rate m_a=60.2kg/sec

mass of flue                m_f=1.26kg/sec

nozzle exist velocity C_n=475m/sec

jet engine speed   C_j =275m/sec

thrust produced   =( m_a)(C_n-C_j)

                             = ((60.2)(475-275) (neglect mass of fule )

                              = 12040N