Visualization Of Single Particle Motion In Model Of Spool Valve Clearance

Spool valve is one of the basic structural forms of hydraulic valve.The clearance height is usually several microns to tens of microns.During the working process,solid particles intruding into the clearance may cause friction of the motion pair,even induce clamping of the spool valve,which seriously affects the reliability of hydraulic system.Therefore,it is of great significance to study the motion characteristics of solid particles in the clearance of spool valves for revealing the mechanism of clamping of spool valves,improving the performance of components and improving the reliability of hydraulic systems.In this paper,experimental method combined with theoretical analysis and numerical simulation are used to investigate the motion characteristics of single solid particle in the model of spool valve clearance.A magnified visualization model is built,the instantaneous movement processes of several particles in the model flow field are recorded by high-speed camera.In theory,the solid particle morphology in the clearance is parameterized.The mechanism of clamping is analyzed,and it is proposed that the rotation of single particle in the clearance may lead to clamping.COMSOL Multiphysics simulation software is introduced.the fluid-structure coupling module is invocated,and the mobile grid method is used as the numerical simulation method.In the aspect of numerical simulation,the instantaneous motion of particles in the two-dimensional amplified model is calculated,and the influence of different shape and size calculation models on particle motion characteristics are considered.It is found that the particle rotation occurs when it moves along the clearance,and the trajectory fluctuates up and down.It's also obtained that when several particles move into the magnified groove,they are involved in the vortex of the fluid and rotate around the wall,which makes it difficult to flow out.In terms of experiments,a magnified visualization model is built according to the spool valve clearance,and the experiment rig for studying the movement of single solid particle in the model is designed and built and some regular cubic particles are produced.The liquid phase is pure water.The clear images of the instantaneous movement process of single particle are obtained by high-speed camera.The experimental results show that the particle rotates continuously when it move along the clearance flow field.It's also obtained that the trajectory of particles are basically the same before they strike the wall,while they strict the wall,different motion trajectories appear.The experimental results show that the particle rotates continuously when it move along the clearance flow field.The rotation of single particle increases the possibility that the particle surface contact with both the surface of the valve body and spool.Because of the non-ideal clearance morphology and the irregular shape of particles,It is possible to induce spool valve clamping.These provide a new train of thought for exploring the mechanism of spool valve clamping caused by solid particles.It is of great significance to prevent particles from entering the clearance,guide particles to flow out of the clearance and eliminate the clamping of spool valves.