Numerical Simulation Of Cavitation Flow In Hydraulic Oil Poppet Valve

Poppet valve is a kind of widely used hydraulic components because of its simple structure,reliable sealing and insensitive to working medium. Cavitation is a natural phenomenon that exist in fluid, it is an unavoidable issue in fluid machinery, which take fluid as their working medium. Cavitation can cause serious damage to fluid machinery. Oil poppet valve takes mineral oil as its working medium, cavitatin in oil poppet valve makes the fluid force and the stability of the poppet more complicated, it also causes cavitation eroding damage for the surface material of the poppet and valve seat. Moreover, serious noise would appear when the cavity collapse. As hydraulic transmission develop for high pressure, high speed and high power, poppet valve also faced with requirements of high pressure and high speed. However, cavitation is an important restricting element for the development of poppet valve. Therefore, studying the cavitation process and mechanism of poppet valve, exploring effect regulars of structures and parameters of poppet valve on cavitation have great practical significance for improving performance and enhancing reliability of poppet valve.This paper adopts numerical method to simulate the cavitation flow in poppet valve.The main content of this paper includes: In chapter 1,the overseas and domestic research status of cavitation flow in poppet valve is summarized, the research background and significance of this study are discussed, and the research focus of this study is established. In chapter 2, the numerical models adopted in this study are briefly introduced. In chapter 3,the effect regulars of different wall functions and parameters of cavitotion model on fluid force and pressure distribution of poppet surface are explored at different flow directions and valve openings under steady sate,and the numerical results are compared with experiment data which comes from the existing literature, by comparison, the numerical models are validated. In chapter 4, based upon the obtained models under steady state, the fluid force of poppet surface is calculated under transient state, it shows that the average value of fluid force under transient state is in accordance with the fluid force under steady state, and the fluid forces on upstream and downstream of valve port have obvious phase shift since the hindrance function of the valve port,thus validates the suitability of numerical models under transient state. Then the transient cavitation process of poppet valve is simulated through two-dimension model, the dynamic evolution process of cavitation flow is obtained and the mechanism of cavitaton process is analyzed. In chapter 5,the cavitation flow of valve port are simulated under different structures and parameters and the effect regulars of structures and parameters on the cavitation of valve port and the fluid force of the poppet is explored. Last chapter summarizes some conclusions in this thesis and suggests the future research proposals.