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| Analysis of cavitation characteristics of marine centrifugal pump based on modified Kunz model |
| WANG Yong1, CHEN Jie1, LUO Kaikai1, LIU Dongxi2, LI Yu1, YAN Jun1 |
| 1.National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.School of Ocean Engineering, Shanghai Jiaotong University, Shanghai 200240, China |
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Abstract Cavitation erosion may be inevitable when a marine centrifugal pump is in operation. Thus, in order to investigate effects of cavitation on the performance of a marine centrifugal pump, the turbulent pressure fluctuation was involved in the Kunz cavitation model to alter the phase transition critical pressure, i.e. vaporization pressure. A marine centrifugal pump with a specific speed of 132.7 was chosen as a study model and its cavitation performance was predicted numerically and experimentally at different flow rates. It was found that the Kunz model and its updated version both were able to capture the critical cavitation condition, but the head curve due to the updated model was in better agreement with the observed curve. In addition, the vapor volume fraction distribution between two blades and the blade loading distribution based on that improved model were analyzed at the design point.The results showed that bubbles were generated on the pressure suction side near the leading edge at first, then a small amount of bubbles occurred on the blade pressure side with decreasing cavitation number. At last, the impeller passages were fully blocked by bubbles, leading to a declined performance for the centrifugal pump. With the decrease of cavitation number, a low pressure zone occurred near the blade inlet edge firstly, then spread along the blade toward the blade outlet, eventually the low pressure covered the blade pressure and suction sides. The blade loading in the middle streamline of blade 5(the blade near the tongue)was smaller than in blade 2(the blade is axisymmetric with blade 5).With the decrease of cavitation number, the pressure on the blade surfaces was reduced, and there was a zero pressure at the inlet of blade 2, this is mainly caused by cavitation aggravation.
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Received: 17 May 2016
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