In order to investigate the dynamical characteristics of the feed pipe - Venturi tube system after pump in a liquid rocket engine

hydraulic vibration experiment were conducted. By generating hydraulic vibration signal after Venturi tube

the pressure fluctuation data at the feed pipes and the thrust chamber manifold were measured

and the transfer function for disturbing this system dynamics was established. The test results indicated that the first resonant response was the main characteristics for the feed system

and the high order resonant peak was unobvious. At the resonant frequency

the pressure oscillation amplitudes were quite high between Venturi tube and main valve

and increased along the flow direction before main valve

but decreased after main valve. A phenomenon of pressure fluctuation transmitting upstream through Venturi tube was discovered. Even the Venturi tube was under the cavitation condition

partial pressure fluctuation could transmit upstream through it

while the Venturi tube also had an evident insulated effect for the whole feed pipe. When the cavitation allowance of Venturi tube was excessively big

the Venturi tube outlet condition was changed from acoustic closed boundary to acoustic open boundary.