For the purpose of researching into the engendering and diffusing of the pressure shock during the starting and the shutting of the rocket tank pressurization system

one-dimensional nonsteady finite difference equations under the Lagrange reference frame were built to simulate the gas flow in the pipes

and ordinary differential equations were calculated numerically based on the dynamic processes of the components

while the frictional loss was computed with a quasi-steady formula.The B-B(Beattie-Bridgeman) function was used to simulate the real-gas effect.The results were presented for the unsteady processes of a representative pressurization system

including the pressure shock that appeared during the starting and shutting operation.It is shown that the pressure shock during the starting changes with large amplitude and the pressure oscillation have shorter period

higher frequency

and rapidly cause of attenuation

while the pressure shock and oscillation changes reversely during the shutting operation.During both the operations

the pressure peak appeared was higher than the pressure in the bottle.The mathematical model and calculating method are validated to be effective in the calculation of the dynamic process of the rocket tank pressurization system.