Simulation Of Flow Field Characteristics And Analysis Of Fluid Cavitation Of Pressure Regulating Valve

The pressure regulating valve is an important control element in the main transmission hydraulic system of ships.Its main function is to meet the requirements of heat dissipation and lubrication of the gearbox and ensure the engagement and disengagement of the wet friction clutch.Whether the hydraulic system can operate accurately and smoothly has become an important index to measure the performance of the pressure regulating valve,which requires the flow field simulation analysis of the pressure regulating valve to clarify the basic characteristics of the flow field.In addition,due to the complex flow channel structure of the pressure regulating valve,the cavitation phenomenon of the fluid in the valve occurs,and the abnormal vibration of the spool under the complex excitation of the flow field will also have a great impact on the working performance of the pressure regulating valve.Therefore,it is of great theoretical significance and engineering value to carry out the research on the flow field characteristics of the pressure regulating valve and the analysis of the cavitation phenomenon of the fluid.In this paper,the steady-state numerical simulation of the flow field in the pressure regulating valve,the transient simulation and influence analysis of the cavitation phenomenon,and the dynamic characteristics of the cavitation flow field are carried out.The main researches in the paper are as follows:(1)Based on the theory of computational fluid dynamics,the steady-state flow field simulation model of pressure regulating valve was established,and the pressure distribution,velocity vector distribution and turbulent kinetic energy distribution of the flow field of pressure regulating valve with different opening were analyzed.It is concluded that the pressure at the orifice drops suddenly,forming impinging jet,and turbulent flow in the oil outlet cavity,showing the phenomenon of fluid cavitation;with the increase of oil temperature,the inlet pressure decreases,the flow velocity increases and the turbulent kinetic energy decreases.(2)The cavitation model of pressure regulating valve was established,and the transient numerical simulation of fluid cavitation phenomenon was carried out.Based on the gas volume fraction at different times,the cavitation intensity of fluid was analyzed,and the evolution law of fluid in the valve from cavitation inception,cavitation development to cavitation collapse was clarified.Through the analysis of the flow field characteristics of the pressure regulating valve in the process of cavitation evolution,it is concluded that the pressure gradient at the throttle mouth is large and the flow rate is high,and the pressure behind the oil outlet chamber is relatively low,which is easy to produce fluid cavitation.(3)The transient simulation model of fluid cavitation of pressure reducing valve with different opening,flow rate and back pressure was established,and the pressure distribution,velocity distribution and turbulent kinetic energy distribution of the flow field were analyzed.Through the research on the distribution law of gas volume fraction in the flow field under different working conditions,it is concluded that increasing the opening and back pressure is conducive to inhibiting fluid cavitation,and larger flow rate is easy to cause fluid cavitation.(4)The dynamic equation of valve core moving process was deduced,and the dynamic analysis model of cavitation flow field of pressure regulating valve was established.The transient flow field was simulated based on sliding mesh technology,and the dynamic characteristics of cavitation flow field,as well as the change law of spool moving track,moving speed,viscous damping force and fluid force at any time were analyzed.With the increase of flow rate,the opening of pressure regulating valve increases,the fluctuation of valve core velocity increases,the viscous damping force on valve core increases,and the cavitation intensity decreases.