Study On Operating Characteristics And Internal Flow Field Numerical Simulation Of Self-cleaning Screen Filter

The filter is the key equipment for micro-irrigation system to handle sediment, research and development of efficient, economical, reliable filter system are the prerequisite to achieve water-saving drip irrigation technology. In this paper, based on indoor test, combined with theoretical analysis,studied on the operating characteristics of the self-cleaning screen filter. In addition, used the CFD (fluid dynamics) software FLUENT to conduct the numerical simulation for drainage system and overall internal flow field.The major research achievements are:(1)Under the clean water condition, contrast and analysis self-cleaning screen filter local head loss’s variation with the flow in different filter mesh and size conditions, fitted the Semi-empirical formula. The clean water curve shows that, the head loss of the filter increases with the influent flow’s increase. When conducted muddy water test, in the same influent flow with the different influent sediment and in the same influent sediment with the different influent flow conditions, experimental researched on the head loss’s variation with filtration time,found that the in influent sediment increased with the influent flow’s increase, filtration cycle of the filter is gradually shorter.(2)Conducted the experimental research on the filter’s best drainage time, with the test results and engineering practice, recommended controlling drainage time between20seconds and30seconds. At the same time, conducted the sand suction opening size’s impact on the flow coefficient of the self-cleaning screen filter drainage system, found that the flow coefficient increases with the sand suction relative inflow area’s increase, but when the relative inflow area increases to a certain extent, the flow coefficient doesn’t change. Based on the test data and combining dimensional analysis established the self-cleaning screen filter drainage flow calculation formula.(3) used numerical simulation method, based on the drainage system and the overall physical model, reasonable assumptions and simplifications of the flow problems within the filter, conducted in-depth analysis and research on the self-cleaning screen filter drainage system and overall internal flow field, achieved the speed of the flow field、pressure distribution、turbulent kinetic energy distribution and velocity vector. Contrast and analysis the internal flow field of the drainage system and filter found that, internal structure of the self-cleaning screen filter still exists in unreasonable and needs to improve it. Used the mean square deviation ERMS inspection of the discrete degree between simulated and measured results, obtained ERMS=0.00156, verified the reliability and accuracy of numerical simulation model of the filter.