Research On Cavitation Of Valve Core Oscillation Based On Overset Meshes

In the hydraulic system,the poppet valve is one of the commonly used valve structures,which usually consists of valve core,valve seat and spring,and is mainly used as a pressure regulating valve to adjust or limit the system pressure.However,the pressure regulating valve often has unstable vibration,which causes the pressure fluctuation amplitude to reach more than ±5 MPa,which in turn causes the pipeline vibration and noise problem of the entire hydraulic system,which has caused a huge impact on the stability and reliability of the entire hydraulic system.influence.Therefore,this paper takes the pilot stage pressure regulating poppet valve as the research object,and studies the cavitation problem during the vibration process of the valve core,which is of great significance for the structural design optimization of the poppet valve and the entire hydraulic system.The main contents and innovations of this paper are as follows:(1)On the basis of the previous experimental research of this research group,the visualization experiment was reproduced using Amesim software,which confirmed that the vibration of the poppet valve is commonly seen in the hydraulic system.(2)Basing on the overset mesh,global hole cutting approach and prism layer shrinkage technology in STAR-CCM+,the dynamic opening and closing of the valve port is realized from the grid level,and explained in detail the mesh composition and method to realize the dynamic opening and closing of the mesh,which solves the problem that the traditional dynamic mesh cannot solve.(3)On the basis of the above overset mesh,combined with the images and data obtained from the visualization experiment,the flow field simulation of the spool oscillation cavitation was carried out by STAR-CCM+,and the simulation results were in good agreement with the experimental results.(4)By placing a probe at the valve port in the STAR-CCM+ simulation,we obtained the flow data which is difficult to measure in the real experiment,and the data was combined with the image to analyze the cause of the oscillating cavitation of the cone valve: the cause of the cavitation when the valve is opened is due to the jet flow,and the reason for cavitation when closing the valve is the low pressure wave caused by the inertia of the liquid;the valve structure designer should pay attention to these two cavitation situations when designing and manufacturing valves.This conclusion provides a certain theoretical support for the design optimization of the poppet valve structure.(5)This paper also conducts an extension study on the basis of the experimental data,setting the moving speed of the valve core to be 0.2 m/s,0.6 m/s,1 m/s,1.4 m/s,1.8 m/s,the valve port opening and closing simulations were carried out under the differential pressure 2 MPa,and the influence of the moving speed of the valve core on the flow at the valve port was studied;The flow conditions of different fixed openings of 0.1 mm,0.3 mm,0.5 mm,0.7 mm,1 mm under the differential pressure 2MPa were also simulated,so as to compare the flow conditions at the valve port when the valve core moved at low speed with the different fixed openings.The results show that the opening and closing speed of the valve core will affect the flow,because of the liquid inertia,also the liquid is not a rigid body,it cannot change the flow state immediately to follow the movement of the valve core;And regardless of the opening or closing of the spool,the spool with low moving speed has little effect on the flow.