Answer Happy

The principal of a ramjet engine is shown below. A supersonic experimental jet equipped wit such an engine is flying at an altitude where the pressure is po = 0.1 bar and the temperature is To = 210 K. The velocity of the jet is twice the local speed of sound. For your first analysis (parts (a) and (b) assume that the jet has an inlet diffuser which allows the sentropic slowing of the incoming air to negligible kinetic energy before it is heated at constant pressure to T2 = 1800 K. The hot air is then expended isentropically in the exit nozzle to the pressure in the environment. For simplicity you may assume ideal gas behavior with constant specific heats. a) Evaluate the specific thrust of the device: 1 = (Vexir - Vinter) (V = velocity: F = force) b) Evaluate the heat to be added to the air per kg of air. F c) Now relax the assumption that the inlet diffuser is isentropic, and recognize that a vertical shock forms in front of the diffuser. Evaluate the specific thrust and heat again. Sketch (roughly) the shape of the diffuser that would be needed in this case. Vrlight V=0 Vexit 0 1 2