Study On Characteristics Of Hydraulic Control Sleeve Throttle Check Valve For Hydraulic Supports

This dissertation focuses on the hydraulic sleeve-reducing one-way valve for FDY400 hydraulic support used in mine hydraulic support.The following work was done on oscillation and cavitation in valve during unloading:1.The paper established a three-dimensional flow channel model based on the geometry parameters of a hydraulically controlled sleeve throttling check valve of a coal company in Zhejiang.The steady state simulation of its internal flow field was stimulated by using Fluent software,and pressure contours and speed vector contours were obtained.In the simulation processes,the valve core opening degree was consistent and the flow field simulations were carried out with different flow pressures so that different pressure and velocity distributions were obtained.2.Based on changing the structure of the valve sleeve and increasing the number of flow holes,the simulations were carried out under the same opening degree and the same pressure difference.And the simulation results of the two kinds of structures were compared and analyzed.Due to the fact that the valve sleeve is under pressure during the unloading of the hydraulically controlled sleeve throttling check valve,the stiffness of the valve sleeve material was tested through one-way fluid-solid coupling.The hydraulic control sleeve throttle check valve plays a role in throttling during the opening process.Based on the unchanged size of the through hole of the valve sleeve,the number of through holes of the valve sleeve is changed,and the pressure difference is the same and the opening degree is different.The influence of the pressure on the outlet pressure of the valve was analyzed.The optimum valve opening range was determined and the opening degree of the valve core was subdivided within this range.The optimal opening of the valve core for throttling function was finally obtained and the number of through-holes.3.Based on the optimal number of through-holes in the valve sleeve,a two-phase flow simulation was performed on the internal flow field using the Mixture model.The obtained results were compared with the simulation results of the flow field with the same boundary conditions and without cavitation models.The effect of cavitation on velocity was studied.In order to study the influence of the cone angle of different valve cores on the velocity of the valve core,two phase flow was simulated(within the range from30~?to60~?),and the integral gas volume fraction contours and velocity vector contours of the vaporized body were obtained.4.The system model of the hydraulic control sleeve throttle type one-way valve model and the hydraulic support is built with AMEsim,and the simulation analysis is carried out.The module parameters were changed,Batch processing through valve sleeve through holes 6,7,8 and the displacement curve,pressure characteristic curve and flow characteristic curve of the valve core were obtained.Then the number of flow holes in the valve sleeve was set to 8,and the cone angle of the valve core was changed by batch simulation.The pressure,flow and displacement characteristics curves of the valve core were obtained,and the simulation results are analyzed.Flow field analysis results show that the maximum speed at the spool is related to the pressure difference.When the opening of the valve port is constant,as the pressure difference increases,the flow velocity at the throttle of the valve core is greater,the pressure at the valve core is smaller.And in the high pressure environment,it will be easy to form cavitation and cause the system to oscillate and form a vortex at the section of the valve core.The number of flow holes also has affects on the velocity of the valve core and the flow rate at the outlet of the valve.As the number of through-holes increases,the speed at the throttle decreases,the flow at the outlet and the minimum pressure at the valve core increases.Through the one-way fluid-structure coupling analysis of the valve sleeve,it is verified that the stiffness of the material meets the requirement when the number of through-holes of the valve sleeve becomes 8.When the number of through-holes is 9,the through-hole of the valve sleeve is deformed seriously,so the through-flow when the number of holes is 8,the valve sleeve structure is optimal.By comparing and analyzing the time-varying curve of valve port pressure with different number of through-holes,it is found that the number of through-holes is 8 at the best.When the number of through-holes is 8,in the case of same pressure difference and different opening degree,the opening degree of the throttle valve opening is 4.2 mm which is the optimum opening degree.By analyzing the results of the flow filed using the cavitation model and the flow field without using the cavitation model,it was found that the cavitation can reduce the velocity at the spool,cause energy loss,and increase the stent unloading time.The velocity at the throttle orifice of valve core is related to cavitation.As the cone angle of valve core increases,the range of cavitation generation decreases but the speed increases.AMEsim analysis results show that with the increase of the valve cone angle and the number of valve sleeve holes,the displacement oscillation curve of the valve core becomes slower,the pressure shock at the valve core becomes smaller,the flow at the valve port becomes larger,and the unloading time will be accelerated.