Blowdown and fluid hammer studies for a satellite reaction control subsystem

Abstract

Blowdown and fluid hammer characteristics are studied for a satellite reaction control subsystem. A flow channel network numerical scheme is used to determine the blowdown pressure profile and the steady state pressure drops in the propellant lines. For the transient fluid analysis, a theoretical model based on the method of characteristics (MOC) is solved to simulate the time-dependent transport behaviour of the propellant flow. Predicted results show that the blowdown pressure profile in continuous mode operation ranges from 24.5 to 5.5 bar throughout the lifetime of propellant usage. Under a tank pressure of 24.5 bar, the predicted peak values of the pressure fluctuations caused by the fluid hammer waves are nearly the same and equal to 25.4 bar at the locations of the latching isolation valve inlet and the thruster valve inlet. The Fourier spectral analysis also indicates that the induced excitation from the fluid hammer pressure oscillations will not resonantly couple with the thruster assembly and fuel lines. In considering the fluid hammer effect due to the abrupt closure of valves, the pressure spikes will not lead to any damage to the propulsion components or lines during normal operation.