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Effects of blade wrap angle on performance of high specific speed centrifugal pump |
HUANG Xi, YUAN Shouqi, ZHANG Jinfeng, ZHANG Xia |
National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract In order to investigate the influence of blade wrap angle on high specific speed centrifugal pump performance under design condition, a single-stage, end-suction centrifugal pump with a specific speed of 185 is taken as study object. Firstly, five impellers respectively with 110°, 115°, 120°, 125°and 130° wrap angles are designed when the rest geometric parameters remain unchanged, then the flow fields in the pump with these impellers are calculated numerically by using software ANSYS CFX 14.5. The results show that the blade wrap angle has a significant impact on external characteristics. If the wrap angle is oversized, the head and the hydraulic efficiency will decline. When the wrap angle increases to 130°, the best efficiency point migrates about 20% to part-load region; in addition, the low pressure zone at the impeller inlet is enlarged with increasing wrap angle, leading to cavitation more easily. When the wrap angle increases from 110° to 115°, the flow in the volute is smoother. However, when the angle is 125°, an obvious vortex region with low velocity appears around the tongue, further it is expanded and moves to the impeller outlet gradually with increasing warp angle. Also, when the wrap angle reaches to 120°, the pressure fluctuation amplitude at every monitoring point is relatively low, showing there is an optimal wrap angle for rotor-stator interaction. The performance of the pump with 120° wrap angle is measured and it is found that the results of numerical simulation are in agreement with the measurements. This study has provided some reference significance to the development of a high specific speed centrifugal pumps with better performance.
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Received: 18 April 2016
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