Research On Steady Flow Force Characteristics Of Conical Throttle Valve

As one of the key components of flow control and safety assurance in hydraulic system,conical throttle valve has the advantages of good sealing,strong flow capacity and low processing cost.However,conical throttle valve is influenced by flow force when it runs.Flow force will cause the self-excited vibration of the conical throttle valve,which will affect the reliability,accuracy and stability of the whole hydraulic system.Therefore,the analysis and study on steady flow force of the conical throttle valve is of great significance to improve the stability of the control when the hydraulic valve runs.The flow characteristics and steady flow force characteristics of conical throttle valve are studied by means of theoretical,numerical and experimental methods.The flow rate,the pressure,the velocity,momentum at the throttle orifice,and the variation of steady flow force of the conical throttle valve are obtained in this paper.The flow force theoretical calculation model of conical throttle valve based on volume control in fluid field is improved according to the Bernoulli’s equation and momentum theorem.And the theoretical expressions of the cross-section area,the pressure distribution on the spool and the calculation formula of steady flow force are derived.The numerical model of the steady flow force of the conical throttle valve is established,and the steady flow force test bench is set up,then the study of steady flow force under different working conditions and structures is completed.The experimental and numerical study of steady flow force acting on the spool of conical throttle valve is carried out,and the variation law of steady flow force characteristics is analyzed.Aiming at the influence of working parameters on steady flow force characteristics of conical throttle valve,the flow characteristics and steady flow force characteristics of conical throttle valve under different openings and pressure differences are studied.The results show that the flow rate increases,the area of high-speed flow increases,the minimum pressure on the spool surface decreases,the velocity at the throttle orifice increases,and the momentum increases with the increase of opening or inlet pressure,which leads to the increase of steady flow force.However,the high-speed flow area in the valve decreases,and the minimum pressure on the spool surface decreases,the velocity at the throttle orifice increases,the momentum decreases with the increase of back pressure of the conical throttle valve,which leads to the decrease of steady flow force.In addition,the incidence angle at the throttle orifice increases with the increase of opening or back pressure,but the incidence angle decreases with the increase of inlet pressure.Aiming at the influence of structural parameters on steady flow force characteristics of conical throttle valve,the flow characteristics and steady flow force characteristics of the throttle valve with different conical angles and diameters of the spools are studied.The results show that the area of high-speed flow increases,the minimum pressure on the spool increases,and the variation of velocity,the incidence angle and momentum at the throttle orifice increases with the increase of the cone angles or the diameters of the spool,which leads to the increase of steady flow force.The influence of the diameter on the flow rate of conical throttle valve can be neglected,and the influence of the diameter on the flow characteristics and steady flow force characteristics is also small when compared with the influence of the cone angle on the flow characteristics and steady flow force characteristics of the conical throttle valve.