Numerical Simulation Of Flow Field And Optimization Of Filter Screen For Y-Type Mesh Filter

As a common filtering equipment in the micro irrigation system,the performance of Y-type net filter affects the operation of the micro irrigation system.In order to explore the hydraulic performance of the net filter,we should fully understand the initial flow field inside the net filter and the flow distribution of the filter element.In this paper,the computational fluid dynamics method is used to simulate the flow field of the filter with three inlet velocities(0.5,1.5,2.5m/s)and three mesh numbers(60,80,100 mesh).Based on the above research,it is found that the flow distribution on the mesh surface of the filter presents a certain rule,and the mesh has a large space for optimization.In order to improve the filtration efficiency and anti clogging of the filter,the flow field of the filter is simulated In order to optimize the clogging part of the filter mesh,the CFD-DEM coupling method was proposed to simulate the particle movement of five kinds of clogged mesh(5,10,15,20,10+10)and different particle sizes(180 μ m,280 μ m)on the 190 μ m mesh filter.The flow field of clogging mesh was simulated and the filtration efficiency was analyzed The results show that:(1)The head loss of the filter is concentrated on the filter element at the outlet side,which accounts for 87% of the total loss;the deceleration area at the outlet side,the plug reflux area and the vortex area;the flow distribution on the filter surface is seriously uneven,and the high flow area is mainly distributed at the outlet side,and the inlet flow velocity changes from 0.5 to 0.5 In the process of M / s increasing to 2.5m/s,the difference between the maximum flow and the minimum flow is 3.3 times.When the mesh number of filter screen is 60,80 and 100 mesh,the difference between the maximum flow and the minimum flow is 3.3,3.1 and 2.3 times.When the mesh number of filter screen is 100 mesh,the positions of the maximum flow and the minimum flow are shifted to both sides.The dead water pressure at the plug is high,the flow velocity is low,and the sediment is easy to precipitate.It is suggested to expand the plug volume to undertake more water In order to improve the flow field distribution,it is suggested to increase the annular plate on the screen to improve the flow distribution on the screen,so as to improve the service life and filtration efficiency of the filter.(2)With the increase of the number of mesh clogging,the head loss of the filter also increases.The flow field law does not change obviously after clogging the mesh,and the pressure field increases with the increase of the number of mesh clogging.When 5maximum flow meshes are clogged,the area of high flow rate area decreases by 4%,and the internal velocity increases The degree field distribution is more uniform,the negative pressure area at the pressure outlet is reduced by 37%,the minimum flow mesh is blocked,the velocity field is cut off,and the negative pressure area at the pressure field outlet basically does not change;in the network flow distribution,when the five maximum flow mesh are blocked,the total flow is the largest,when the five or ten mesh are blocked,the coordinates of the maximum flow position are shifted outward,and the minimum flow position is shifted outward When 15 or 20 mesh are blocked,the maximum flow is concentrated in the center of the high flow area.Compared with no blocking,when 5,10 or10+10 mesh are blocked,the area of the high flow area increases by 19.2%,18.3% and22.9%,which improves the filtration efficiency of the filter screen.(3)Blocking the mesh can increase the passing rate of sediment particles,but also affect the uniformity of its distribution.When 5,10 and 10+10 mesh are blocked,the passing rate of particles will increase and become more uniform.With the increase of mesh clogging on both sides of the shaft,the upper end and the lower end of the filter screen at the inlet side,the number of sediment particles on the mesh surface decreases,and the plug particles increase,and the sediment distribution on the mesh surface becomes uniform,that is,plugging the mesh can improve the anticlogging performance of particles in the filter.Combined with the changes of flow field,water and sediment movement,particle distribution and sediment passing rate in the filter,it is verified that plugging the mesh can effectively improve the anti clogging performance and filtration efficiency of the filter,and the best filter optimization scheme is selected,that is,plugging five maximum flow mesh.To sum up,through the numerical simulation of the flow field of the Y-type mesh filter under different working conditions,this paper puts forward the theoretical basis for the structure optimization of the mesh filter,and puts forward the optimization scheme of the mesh to block the maximum flow,verifies its feasibility,selects the best scheme,and provides a new idea for the structure optimization of the filter.