发动机泵后管路-汽蚀管系统水力激振试验

为了研究火箭发动机泵后管路-汽蚀管系统动力学特性，开展水力激振试验。在汽蚀管下游引入水力激振信号，测量供应管路和推力室头腔的脉动压力，建立描述系统动力学特性的传递函数。结果表明:该系统主要表现出1阶谐振特征，高阶谐振峰不明显。在谐振频率下，汽蚀管出口至氧主阀之间管路上脉动压力的幅值整体较高，脉动压力幅值沿流向逐步增大；经过氧主阀后，压力振荡幅值沿流向快速降低。发现了压力脉动通过此汽蚀管向上游传播的现象:即使汽蚀管处于汽蚀状态，仍存在部分压力脉动通过汽蚀管逆向传播至上游管路；而汽蚀管对整个管路仍然起到了明显的隔振效果。在过大的汽蚀裕度下，汽蚀管出口由声学闭端边界逐渐向声学开端边界转变。 

Experiment for hydraulic vibration onrocket engine feed pipe-Venturi tube system after pump

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.