Experimental Study On Sediment Interception Of Y-Type Mesh Filter

Y-type mesh filter is a commonly used filter equipment in agricultural irrigation field,its performance affects the normal use of the whole micro-irrigation system.However,the clogging problem of the filter screen in the application process is becoming more and more prominent,which directly affects the working efficiency of the filter,and even causes the scrap of the micro-irrigation system in serious cases.This is also one of the important reasons for the rapid development of micro-irrigation industry since the introduction of micro-irrigation technology in China.The performance of mesh filter is divided into hydraulic performance,filtration accuracy and anti-blocking ability.In order to improve the filtration performance of Y-type mesh filter,a new concept of filter interception rate was proposed.The experiment results are designed for 5 different inlet pressures,7 different filter screen diameters and 13different sediment median particle sizes,and three factors and three levels orthogonal tests.The main conclusions are as follows:(1)The blocking process of the filter screen in the operation of the filter is as follows:the initial state is unobstructed,no blocking phenomenon occurs,and the blocking rate is zero;At the fifth minute,the medium blockage occurs on the mesh,and the interception phenomenon begins to appear,resulting in the interception rate.The phenomenon of"building Bridges"and"building houses"appeared in 5～15 minutes,and the filter screen was initially blocked,and the interception phenomenon and interception rate became larger.Stable filter cake was formed on the surface of the filter screen for 15～30 minutes,and the interception phenomenon was significant,and the interception rate reached the maximum;(2)The interception rate of the filter increases with the increase of the inlet pressure.The higher the inlet pressure is,the faster the flow rate will be.The more sand particles enter the filter,the earlier the formation of filter cake,the earlier the interception phenomenon occurs,and the higher the interception rate is.In addition,the larger the inlet pressure is,the larger the flow rate is,the larger the backflow area and vortex area formed inside the filter are,and the fine sand particles are difficult to break away from the current drag force and then enter and accumulate in the vortex area,and eventually deposit in the lower end of the filter,resulting in a larger interception rate.Through calculation and experiment,it is found that the critical inlet pressure can not only maintain the stable filtration state,but also improve the interception rate,and the reference selection of the critical inlet pressure for the mesh aperture and the median particle size in irrigation engineering is given;(3)The interception rate of the filter is affected by the median particle size ratio Y of the mesh aperture to the sand particle size.When Y<[1.80,1.88],the interception rate is higher with the larger mesh aperture,while the opposite is true with Y>[1.80,1.88].Determine the inlet pressure,mesh aperture-sand median diameter than Y,and the relationship between the number of mesh aperture and interception rate and fitting out the calculation formula for calculation of interception rate,fitting formula of the average error of 1.09%,the average error rate of 3.20%,determination coefficient R~2 is 0.94,the model accuracy and high reliability,and puts forward the median particle size under the condition of actual irrigation engineering mesh aperture in the selection of reference;(4)Test observation found that the inlet pressure,the greater the flow velocity,the greater the grains of sand in the more concentrated the interception location on the screen,and distribution in the export side,so you can consider to reduce exports face skeleton density,increase the punching area,turn into former after the small filter outlet cone,or to increase the flow area of circular arc shape,so as to reducing the speed of filter blockage,enhance the operational performance of the filter effect;(5)The orthogonal test results show that the order of the influence of various factors on the interception rate is as follows:inlet pressure,mesh diameter and median sand particle size.The inlet pressure has a significant influence on the interception rate,the mesh diameter has a significant influence on the interception rate,and the median sand particle size has no significant influence on the interception rate;(6)Experimental comparison and analysis of different conditions,different times of the water sand particle size grading found mesh is higher than the expected the actual filtration precision of filtration precision,analysis of different aperture mesh filter in different entrance pressure condition of stable condition when the actual filtration precision compared with its expected filtration precision increased by 25.98%on average,more than a quarter.At the same time,the commonly used reference selection table of actual filtration precision is given;(7)For reference the actual filtration precision filter type selection of hydraulic performance and flow capacity comparison,discovered in the irrigation works on the selection of reference actual filtration precision average head loss and flow loss was reduced by 25.57%and 27.25%,respectively,than the same quarter,refer to the actual filtration precision filter selection on the hydraulic performance of the filter and flow capacity by increased significantly;In conclusion,it can be concluded from the test that,due to the influence of inlet pressure,mesh aperture and median sand particle size on filter interception rate and filtration effect,the selection and adjustment of irrigation parameters and equipment can be carried out according to the conclusion of this study in the actual irrigation engineering application of Y-type mesh filter to achieve the best filtration effect.