Hydraulic vibration experiment on a rocket engine feed system after pump

The dynamical characteristics of liquid rocket engine propellant feed system after pump have important effect on the stability of thrust chamber. In order to investigate the dynamical characteristics of the propellant feed system after pump in an engine, the hydraulic vibration experiments within the medium and high frequency ranges of the full scale engine feed system after oxidizer pump were conducted. Test data indicate that resonance characteristics of the engine feed system were excited. Under the test condition, the first four resonant frequencies and the vibration modes can be clearly revealed. The first resonant frequency had highest response amplitude, while the second resonant response amplitude was lower than the first one, and similar to the third one. The fourth resonant response amplitude was further lower than the third one. Under the external pressure fluctuation, this engine feed system after pump can easily achieve the resonant condition. When the fluctuation frequency was close to the resonant frequencies of the feed system, the pressure oscillations along the feed system presented obvious resonant wave shapes. The position of the injector manifold is always the wave node of pressure oscillation, namely the wave anti-node of flow oscillation, under different resonant frequencies.