中比转速离心泵叶片穿孔空化性能分析

Cavitation Performance Analysis of Blade Perforated Centrifugal Pump

为分析叶片穿孔对泵空化性能的影响,该文以中比转速(ns=129)离心泵为研究对象,通过设计不同穿孔直径(D=2,3和4 mm)及穿孔角度(α=-25°,5°,35°和65°)的12种叶片头部穿孔方案,在初生空化和临界空化工况下,对中比转速离心泵进行数值模拟计算。研究发现:空化工况下穿孔方案对离心泵扬程和效率影响不超过1%,叶片进口端穿孔可以平衡叶片工作面与吸力面压力差,将各流道单个低压区阻断为两个,有效改善叶轮内压力分布,减小叶轮叶栅切面气泡体积分数并抑制空泡产生;适当的穿孔角度与穿孔直径搭配方案在初生空化和临界空化工况下均有益于提升离心泵抗空化性能,研究得出的最佳穿孔方案为方案H(D=3和α=35°)、方案I(D=4和α=35°)和方案J(D=2和α=65°)。

In order to analyze the influence of blade perforation on the cavitation performance of the pump,a centrifugal pump with medium specific speed(n s=129)is taken as the research object.Twelve kinds of blade head perforation schemes with different perforation diameters(D=2,3,4 mm)and perforation angles(α=-25°,5°,35°,65°)are designed to numerically simulate the centrifugal pump with medium specific speed under the conditions of incipient cavitation and critical cavitation.It is found that the perforation scheme has no more than 1%effect on the head and efficiency of the centrifugal pump under cavitation conditions.The perforation at the inlet end of the blade can balance the pressure difference between the blade working surface and the suction surface.It blocks the single low pressure zone of each flow channel into two,which can effectively improve the pressure distribution in the impeller,and reduce the bubble volume fraction in the cascade section of the impeller and inhibit the generation of cavitation.The appropriate combination of perforation angle and perforation diameter is beneficial to improve the anti-cavitation performance of centrifugal pump under the conditions of incipient cavitation and critical cavitation.The best perforation schemes are scheme H(D=3,α=35°),scheme I(D=4,α=35°)and scheme J(D=2,α=65°).