Calculating drainage flow rate through selfcleaning screen filters
LUO Xiu-Ping, LIU Huan-Fang, ZONG Quan-Li, YI Ping
(1.College of Water Conservancy and Architectural Engineering, Shihezi University, Shihezi, Xinjiang 832003, China; 2.Survey Planning and Design Institute, Xinjiang Production and Construction Corps, Urumqi, Xinjiang 832000, China)
According to the investigation of the impact factors on the flow rate， it was found that the drainage flow rate through a selfcleaning screen filter Qp is determined by a flow coefficient.In order to investigate variation features of the flow coefficient， a series of experiments were conducted at various dimensionless inlet crosssection areas of the sand suction component in a selfcleaning screen filter. It was observed that the coefficient increases with opening initially. However, once the opening rises to a certain level, the coefficient no longer changes with the opening and tends to arrive at a constant. The established flow coefficient formula showed that when the dimensionless inlet crosssection area is more than 0.15, i.e. the height of the inlet is bigger than 500 mm (in the experiments, the width of the inlet was kept to be 300 mm), the change in the flow coefficient caused by the dimensionless area is less than 0.5%. This suggests the flow coefficient almost no longer depends on the dimensionless inlet crosssection area. Such a theoretical outcome is consistent with the experimental observations. Finally, an empirical formula was proposed to calculate the drainage flow rates through a selfcleaning screen filter based on the flow coefficient established. Interestingly, the root mean square error (RMSE) is 0.001 74 only, showing the formula has an excellent accuracy.
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