Question

A small rocket motor, fueled with hydrogen and oxygen, is tested on a thrust stand at a simulated altitude of 10 km. The motor is operated at chamber stagnation conditions of 1500 K and 8.0 MPa (gage). The combustion product is water vapor, which may be treated as an ideal gas. Expansion occurs through a converging-diverging nozzle with design Mach number of 3.5 and exit area of 700 mm². Find the pressure at the nozzle exit plane. Calculate the mass flow rate of exhaust gas. Determine the force exerted by the rocket motor on the thrust stand.

Answer 1

I have helped you with two of these nozzle flow problems already and would like to see you make an effort. I suggest you use isentropic flow tables and a specific heat ratio of 1.3 for water vapor, but you should confirm that. There is a formula for the thrust that involves the mass flow rate the exit velocity, as well as P(exit) and
P(ambient). You can get P(ambient) from the simulated altitude.