The sketch shows a test set-up for measuring the thrust of a liquid oxygen-liquid alcohol rocket. The alcohol and oxygen enter at section 1 with a velocity of 15 m/sec, at a pressure of 50 atm, and with a mass rate of flow of 5 kg/sec. The inlet pipe for the alcohol and oxygen is very flexible, so that the force it exerts on the combustion chamber is negligible. In the exit place of the jet nozzle, at section 2, it is known that the pressure is 2 atm and the exit-plane area is 65 cm2. The force exerted on the scale at the left when the silencer is not used is 1800 N. Atmospheric pressure is 100 kPa.
Estimate the jet velocity in the exit plane of the nozzle when the silencer is not used.