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压力脉动和空化特性是影响离心泵稳定运行的两个重要因素。针对国内某大型调水工程的立式带导叶离心泵,在保证蜗壳、导叶和叶轮出口直径等设计参数一致的情况下,设计了两种不同形式的模型叶轮,并进行了模型泵的同台试验。两个叶轮的比转速都为106.43,叶片数分别为7和9,叶轮流道、叶型也不相同,其中,对9叶片叶轮叶片进口边进行了“C形”修型。结果表明,两种叶轮形式离心泵内部压力脉动的频率成分及其分布特性类似,总体上都为叶片通过频率及其谐频,且该频率的压力脉动能通过叶轮流道逆水流方向向进口端传播。叶轮形式对压力脉动幅值的影响比较显著,相比7叶片叶轮,9叶片叶轮的压力脉动幅值降低了10%以上。同时,对叶片进口边修型后,初生空化得到有效延迟,设计流量点附近的临界空化余量下降约10%。适当提高叶片数与叶片进口边修型可显著提高离心泵空化性能。
Pressure pulsation and cavitation characteristics are two important factors affecting the stable operation of a centrifugal pump. A vertical guide vane centrifugal pump with a large water diversion project in China has designed two different types of model impellers with the same design parameters such as the volute, the guide vane and the outlet diameter of the impeller. The model pump The same stage test. The specific rotational speed of the two impellers is 106.43, the number of blades is 7 and 9 respectively, and the impeller runner and leaf pattern are also different. The “C-shaped” shape of the inlet of the 9-bladed impeller blades is carried out. The results show that the frequency components and distribution characteristics of the internal pressure pulsations of the centrifugal pump with two types of impeller are similar, and the frequency and the harmonic frequency of the blade are overall, and the pressure pulsation of the frequency can flow through the impeller flow path to the inlet end spread. The influence of the impeller form on the pressure pulsation amplitude is significant. Compared with the 7-blade impeller, the pressure pulsation amplitude of the 9-blade impeller is reduced by more than 10%. At the same time, after the modification of the inlet edge of the blade, the initial cavitation is effectively delayed, and the critical cavitation margin near the design flow point is reduced by about 10%. Appropriate to improve the number of leaves and blade inlet edge modification can significantly improve the performance of centrifugal pump cavitation.