#### (Solved): 4. (40 Points) Consider A Turbojet Afterburner Pictured Below, Which Burns Fuel With Combustion Prod ...

4. (40 points) Consider a turbojet afterburner pictured below, which burns fuel with combustion products after the turbine. We will treat the mixture of air and combustion products as if it were air. After the turbine, the air has T1 = 600 K and P1 = 500 kPa, with Ma1 = 0.1. At this point, the air passes through the afterburner, where 1000 kJ/kg of heat is added to the air before it reaches the afterburner exit (state 2). Next, the air at state 2 passes through a converging-diverging nozzle. The atmospheric pressure at the flight altitude is 18 kPa. a. Fill in the following table (ignoring the indicated boxes), assuming the air flow is supersonic in the diverging section of the nozzle, and the nozzle is perfectly expanded. Location Temperature Pressure Mach Number Stagnation (kPa) Temperature (K) Pressure (kPa) Afterburner Inlet (1) Afterburner Exit (2) Nozzle Exit (K) (3) b. How much higher is the thrust with the afterburner than when the afterburner is off (so there is no heating), assuming the same mass flow of air passes through the nozzle, and the nozzle geometry can be varied to maintain perfect expansion? Neglect frictional effects in the afterburner and nozzle, and neglect the effects of ambient pressure and inlet air velocity on thrust. Pambient = 18 kPa Afterburner 1000 kJ/kg Afterburner State 2 Afterburner exit State 3 Exit elites State 1 Afterburner inlet T1 = 600 K P2 = 500 kPa Ma, = 0.1