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| PIV measurement of internal flow field in open-impeller flow passages of centrifugal pulp pump |
| ZHANG Qihua*, YAN Zhaoxu, ZHANG Weidong,KANG Shun |
| National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract In order to investigate the influence of fiber particles on liquid flow field in the open impeller of a centrifugal pulp pump, the model pump was constructed by using plexiglas materials, and the flow in the impeller passages was visualized by PIV experimentally with water and 0.1% hair fiber suspension, respectively. The experimental results showe that the flow in the impeller passages is stable at high flow rates, and there are no vortex and low-velocity region in the passages. At low flow rates, a low-velocity zone starts to occur near the blade pressure side in the middle portion of a passage when it rotates close to the volute tongue. Additionally, the size of the low-velocity zone gradually increases with decreasing distance of the passage to the tongue and reducing flow rate. Specially, there is no obvious low-velocity zone generated in the passages far away from the tongue.Due to blade twist, the re-lative velocity varies in the blade spanwise direction, and the smaller the twist, the less the velocity varies.When transporting the hair fiber suspension, the relative velocity of liquid phase decreases in the impeller passages owing to the influence of hair fibers, resulting in an increased area of the low-velocity zone under low flow rate conditions.At high flow rates, the existence of hair fibers makes the relative velocity distribution of liquid phase fluid more uniform.
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Received: 17 April 2019
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