Research On Solid-Liquid Two-Phase Flow And Erosion In Ball Valve With Different Openings

The ball valve are widely used in pipeline hydraulic conveying systems due to its reliable structure.Solid particles are present in the medium to be transported.Solid particles impact on the valve surface under the driving of water flow,which makes the ball valve face the risk of erosion damage.Due to the change of the flow cross section during the opening and closing process of the ball valve or the adjustment of the flow rate,the flow of the two phases inside the valve is changed,so that the solid particles exhibit different distribution characteristics inside the flow passage,which in turn causes the ball valve and the main components of the pipeline.The surface forms different erosion characteristics.In addition,changes in the diameter of the solid particles and changes in the placement of the ball valve also affect the solid-liquid two phases flow characteristics inside the ball valve.In this paper,experimental and numerical methods are used to study the solid-liquid two-phase flow characteristics and erosion distribution in the ball valve by changing the opening,particle diameter and placement of the valve.To optimize the structure of two-phase ball valve and provide theoretical support for the anti-erosion design of ball valve.The main contents of this paper are as follows:(1)Study on solid-liquid two-phase flow and erosion characteristics of ball valve with different relative openings: By calculating the fluid source equation,the solid particles are subjected to force analysis,and the erosion calculation formula is added.The two-phase flow and erosion calculation model of the process valve based on CFD-DEM coupling method is formed and verified.Based on this,the calculation of flow and erosion of the ball valve is carried out,in which the inlet speed is 3m/s,the particle mass flow is 0.45kg/s,and the relative opening is 20%,35%,50%,65%,80%.The particle diameters were 50?m,100?m,150?m,250?m,350?m,and 500?m,respectively.By analyzing the calculation results,it can be seen that the erosion of the wall of the ball valve mainly occurs in the spool runner,downstream pipeline,sphere surface and inner surface of the valve chamber;at the same inlet velocity,the kinetic energy of particles from the high-speed jet decreases with the increase of relative opening,and the erosion degree of the valve core and the wall of the pipe decreases accordingly.When the opening is 20% and 35%,the erosion rate decreases with the increase of particle diameter.When the relative opening is more than 35%,the erosion rate decreases first and then increases..(2)The influence of placement mode on the surface erosion of main parts of ball valve: A two-phase flow erosion test bench was built and the experimental model of the ball valve was designed.The solid-liquid two-phase flow-induced erosion experiment on the inner surface of the ball valve was carried out,and the numerical calculation was carried out.The opening angle of the valve is 50 degrees,60 degrees,70 degrees and 80 degrees,and the placing mode is horizontal and vertical respectively.The accuracy of the calculation is further verified by comparing the measured data with the numerical results.The results show that the placement mode of the ball valve has a great influence on the two-phase flow and erosion distribution inside the valve;at a small opening,the surface of the erosion disc will form corrugated texture under the impact of particles;when the placement mode changes from vertical to horizontal,the distribution of particles will easily gather on part of the wall due to the change of gravity direction.The formation of a protective layer near the surface reduces the erosion rate.