Numerical Simulation Of The Sound Field And Experiment Research Of Valve Inner Leakage

This paper takes the engineering problem of pressured valve gas inner leakage as background. Acoustic detection and evaluation of pin valve,ball valve and gate valve are studied. Because the flow state of fluid in the valve is complicated, and it has interaction between gas jet flow filed and their sound filed, it is difficult to analyze characteristics of sound filed truly through the theory method.Using the method of numerical simulation combined with experiment, the sound filed of valve gas inner leakage is simulated, then the origin of leakage noise and the characteristics of sound filed are analyzed. At last, the simulation results give theory supporting to acoustic detection technique of inner leakage. High speed jet generated by inner leakage not only radiates quadrupole noise, but also sound transmission is disturbed as refraction by the non-uniformity gas flow. So it is basic for numerical simulation of sound field to analyze the flow state, the position and amplitude of jet's noise source, and distribution of disturbance speed. Simulation of inner leakage flow field make the Reynold's average N-S equation and k-εturbulence model as control equation, which is discretized by second order upwind of finite volume method. Fourth order Runge-Kutta scheme is used for time integration, and SIMPLEC method is used to compute flow velocity and pressure coupled. The function of velocity distribution is confirmed by simulation results of flow filed, that provides a foundation for simulation of valve gas inner leakage.The numerical simulation of noise field uses the acoustic wave equation with disturbing as control equation, and uses non-condition stability,high order weighted average method with three floors implict difference to separate the equation. Clayton-Engquist-Majda non-reflect and Dirichlet all-reflect have been applied on boundary condition, meanwhile, the results can be visible by programming and using picture display function of MATLABL. The sound generated by axisymmetric jet and the inner leakage sound field of three kinds of valve can be simulated. Considering the factor of different pressure and inner situation, inner leakage sound field and characteristics can be analyzed at the same time, and rule of leakage noise is found.By establishing acoustic test device simulating the valve inner leakage, the signal generated by inner leakage of different valve can be collected, the experiment data of acoustic amplitude and inner leakage rate are gained, the numerical simulation results are proved accurate.