流量调节器在泵压式供应系统中的动力学特性

针对某型流量调节器及泵压式供应系统,建立了描述其动态特性的频域分析模型,研究系统在出口压力扰动下的频率响应特性以及系统的固有稳定性.结果表明调节器在系统中的位置对系统高频范围内的频率特性影响很大.当供应系统总压降保持一定,增大出口局部流阻的压降能降低系统的谐振峰.当出口局部阻力较小,管路长度比例合适时,系统能够出现自发的不稳定.出口局部阻力越低,系统的总管路长度越大,则系统稳定性越差,不稳定的管路长度比例区间就越大.系统产生不稳定的机理是,在合适的管路长度比例下,调节器第二道节流口所分成的两截管路的声学频率相匹配,且流量调节器处于固有频率的压力波腹,滑阀始终受到频率一致、较大幅值的脉动压力的作用,使得滑阀在固有频率下产生明显的随动响应,对系统形成正反馈.在系统的阻尼耗散作用不足时,形成了耦合的不稳定系统.

Dynamical characteristics of flow regulator in pump feed system

The frequency domain analytical model was developed to describe the dynamical characteristics of flow regulator and pump feed system. The system＇s frequency response characteristics under outlet pressure disturbance and the system inherent stability were investigated. The results show that, the position of regulator in the feed system has strong influence on the system frequency characteristics in high frequency range. When total pressure drop of the feed system keeps constant, enlarging the outlet local resistance＇s pressure drop can reduce the system resonant peak. Under low outlet resistance and appropriate pipe length ratio, the spontaneous instability of the system occurs. The low the outlet resistance and the long the total pipe length are, the worse the system stability and the large the unstable region of pipe length ratio become. The mechanism of system instability is that, with the appropriate pipe length ratio, the acoustic frequencies of the two pipes divided at the regula- tor second throttle are matching, and the regulator is at the pressure wave antinode with inherent fre- quency, thus the slider is always under the effect of the same frequency and relative higher amplitude pressure fluctuation, and the slider produces obvious servo response at the system natural frequency and cause a positive feedback to the system. If the damping dissipation of the system is not enough, the coupled instable system is created.