气动阀门自激振动机理及动态稳定性

基于弹簧振子的扰动响应特性,提出了气动阀门气固耦合自激振动的稳定性机理.以单向阀为例,根据小扰动原理,构建系统的气固耦合动力学模型及稳定性模型,通过求解线性方程组的特征根,得到了单向阀系统的稳定工作区间及参数影响特性,稳定性分析模型的有效性由单向阀气动试验验证.对于单向阀,存在压力-流量的临界稳定性曲线.工作压力一定时,当单向阀工作流量小于相应压力下的临界稳定流量,单向阀处于不稳定状态,一个微小的扰动都将会导致阀芯周期性振荡;反之,单向阀工作稳定,阀芯将处于稳定开度.增加单向阀阀芯阻尼、弹簧刚度及减小阀门进口直径在一定程度上将有助于提高单向阀的工作稳定性.

Mechanism of self-excited vibration and dynamic stability for pneumatic valves

Based on the disturbance response characteristics of spring oscillator, the mechanism of pneumatic valves' self-excited vibration due to fluid-structure interaction was developed. Moreover, adopted small signal stability analysis theory, the dynamic mathematics model and stability analysis model for a check valve were constructed, and the critical stable curve and the parameter impact rule of the check valve were obtained by solving the characteristics root of the linear equations. The validation of stability analysis model was preformed by the pneumatic experiment of a check valve.The results indicate that there is a critical stability curve of pressure and mass flow, and the critical mass flow is one-to-one corresponding to the working pressure. If the mass flow is less than the critical mass flow at a constant working pressure, the check valve become unstable which causes the cyclical motion of the spool excited by a very small distribution; otherwise, the check valve is stable and keeping a fixed opening. Moreover, increasing the damp coefficient and the inlet diameter or decreasing the spring stiffness partly enlarge the stable region, which can be used for the optimum design of check valve.