环形密封对离心泵转子系统稳定性影响的数值研究

Effect of annular seal on stability of a centrifugal pump rotor system

环形密封中流体产生的激振力是导致离心泵转子-密封系统失稳的重要因素。文章采用非线性密封Muszynska模型建立了离心泵转子-密封系统动力学模型,利用四阶Runge-Kutta法将二阶微分方程转化成了一阶微分方程,同时将打靶法和Floquet理论相结合,对离心泵转子-环形密封系统不同密封参数情况下的非线性稳定性及其分岔问题进行了研究。结果表明,在转速较低时,系统是稳定的周期涡动,随着转速的提高,系统将产生Hopf分岔进入准周期运动而不再稳定,进一步研究发现系统稳定性与密封参数有着重要关系,适当增大密封压差,减小密封间隙和减小密封长度可以提高离心泵转子-密封系统稳定性,计算结果为离心泵转子-密封系统的设计以及定性控制系统的稳定性提供了理论依据。

The excitation force generated by fluid in an annular seal is an important factor for instability of a centrifugal pump rotor-seal system. Here,a centrifugal pump rotor-seal system＇s dynamic model was established with Muszynska nonlinear seal model,and the second-order differential equations were coverted into the first order differential equations by using the fourth-order Runge-Kutta method. The shooting method was combined with Floquet theory to study the stability and bifurcation of a centrifugal pump rotor-seal system under different seal conditions. The results showed that the system is stable with lower rotor speed; Hopf bifurcation and quasi-periodic motion emerged with increase in rotor speed; the system stability is closely related to sealing parameters,it is improved with increase in seal pressure difference,and decrease in seal gap and seal length. The results provided a theoretical basis for design of centrifugal pump rotor-seal systems and qualitative control of system stability.