In order to investigate the water hammer dynamics of spacecraft propulsion system during the priming and shutdown processes

dynamic simulation of a certain unified propulsion system (UPS) was conducted firstly based on UPS simulator modeled previously.Then the water hammer suppression effect of orifice and bent pipe on the propellant supply pipeline was analyzed thoroughly.Results show that water hammer phenomena occur obviously in almost the whole propulsion system during the priming and shutdown processes.However

the frequency and the peak pressure of water hammer during the priming process are both lower than that of the shutdown process

especially the peak pressure.The results also show that both the orifice and the bent pipe can suppress the oscillation of pressure and flow rate significantly during the priming processes

but only orifice with small diameter can suppress the water hammer effectively during the shutdown process.Moreover

in contrast to their weak suppression of water hammer during the shutdown process

bent pipe can suppress the oscillation of flow rate especially effective in the priming process.