Failure Analysis for Pressure Fluctuation of Oxygen Phase-change Heat Exchanger in Rocket Engine

Pressure fluctuation occurred in the inlet and outlet of the helically coiled phase-change heat exchanger in the rocket engine during the ground test and it would result in failure during the flight mission. Failure analysis was conducted by flow and heat simulation for the oxygen flow in the phase-change heat exchanger based on the distributed parameter model (DPM) to explore the mechanism of the pressure fluctuation. The thermal parameters including pressure and temperature along the flow tube is calculated by the use of the local physical properties and the local heat transfer & friction coefficients. It can be concluded by the contrast of the oxygen’s thermal process that the pressure fluctuation is caused by the low vaporization pressure. When the vaporization pressure is close to the critical pressure, the intense physical properties fluctuations due to the extremely high thermal expansion coefficient results in the flow instability which causes the pressure fluctuation.