Experimental Study On Flow Channel Structure Optimization Design And Filtration Performance Of Disc Filter

Objective:As the core equipment of drip irrigation system,the filter ensures that the emitter is not blocked by impurities when purifying water quality,so that the drip irrigation system can operate normally.Therefore,it is great significance to develop the advanced water-saving equipment is for saving water resources and improving the efficiency of drip irrigation system.The disc filter is widely used in secondary filtration due to its controllable accuracy.However,the existing disc filters are mostly linear flow channel structures,and the water flow always contacts with the flow channel wall after entering the disc filter,resulting in a large head loss.Based on this problem,this study innovatively proposes a new type of filter laminated,namely discrete flow channel laminated,by carrying out the optimization design of laminated flow channel structure,and improving the hydraulic performance of disc filter by reducing the contact friction between water flow and flow channel wall.Methods:The head loss of the disc filter with discrete flow channel structure under different flow rates were measured through physical experiments.In order to verify the reliability of the numerical simulation,the output flow of this study is compared with the actual flow.Fluent19.0 was used to numerically simulate the three stacking modes of discrete channel laminations under clear water conditions,analyze the distribution characteristics of the flow velocity field,and optimize the structure of discrete channel lamination.The hydraulic performance and filtration performance of the optimized stacking method are tested,and the test results were compared with those of the traditional linear flow channel disc filter in China.The head losses of the two-disc filters were mainly tested under the condition of clear water,and the head loss,sediment retention,particle size distribution,and uniformity of sediment distribution in the flow channel were tested under the condition of sandy water.Results:(1)The head loss of discrete flow channel disc filter is smaller than that of linear flow channel disc filter.Under the condition of clear water,the head loss of a discrete channel disc filter is 33.5%～50%lower than that of a linear channel disc filter.Under the condition of sandy water,the head loss of the discrete channel disc filter is 18.85%～47.07%lower than that of the linear channel disc filter.(2)By analyzing the velocity field,it can be obtained that the average cross-sectional area of the discrete channel is larger than that of the linear channel,and the cross-sectional area is inversely proportional to the flow velocity,so the head loss of the discrete channel disc filter is small.By analyzing the pressure field,it is found that both sides of the wall of the linear channel have an impact on the head loss along the line,and the head loss along the line is dominant in the linear channel;in the discrete flow channel,the convex spacing decreases gradually along the radial direction,and the local head loss is dominant,but the convex separation arrangement reduces the head loss along the path.Therefore,the head loss along the route is the main reason for the large head loss in the linear channel.(3)When the flow rate is 1.5 m~3/h,the average sediment retention of the discrete channel disc filter is 6.32%higher than that of the linear channel disc filter.The separation and arrangement of the convex platform provide more possibilities for the development of the vortex zone in the flow,compared with the linear channel disc filter.(4)The blocking uniformityημof the discrete channel disc filter is 1.5～2.5 times lower than that of the linear channel disc filter.Theημvalue of the discrete flow channel filter decreases with the increase of sediment concentration,so the discrete flow channel filter can also maintain a stable filtration effect under high sediment concentration.(5)Under different influent sediment concentrations,the proportion of particles with particle size less than 53μm intercepted by the discrete channel filter is higher than that of the linear channel filter,indicating that the discrete channel filter has better sediment interception capacity.Conclusion:The hydraulic performance and filtering effect of the disc filter in the discrete flow channel are related to the structure of the laminated flow channel.The improvement of the hydraulic performance is mainly based on the separation and arrangement of the convex platforms in the discrete flow channel,which provides a large effective flow area and reduces the contact friction between the water flow and the wall.Considering the influence of discrete channel lamination on the working performance,the working performance can be improved by optimizing the convex size and the convex superposition method.