偏工况下离心泵叶轮内失速特性研究  

Rotating stall in centrifugal pump impellers under part-load conditions

作　　者：冯建军[1] 王晨 罗兴锜[1] 吴广宽[1] 朱国俊[1] FENG Jianjun;WANG Chen;LUO Xingqi;WU Guangkuan;ZHU Guojun(Institute of Water Resources and Hydro-electric Engineering, Xi＇an University of Technology, Xi＇an 710048)

机构地区：[1]西安理工大学水利水电学院,西安710048

出　　处：《水力发电学报》2018年第5期117-124,共8页Journal of Hydroelectric Engineering

基　　金：国家自然科学基金(51679195;51339005;51479167)

摘　　要：旋转失速是离心泵内部常见的一种不稳定流动现象,通常发生在小流量工况下,会引起水泵运行时的性能不稳定,严重时会引起整个泵系统的共振。采用CFD方法对某离心泵内的失速现象进行数值模拟,并从外特性曲线、内部流动状况及频域分析三个方面与已有的实验结果进行对比。采用阻塞系数来量化表达叶轮内部的失速状况。结果表明,在0.35倍最优流量(0.35Q_0)下,在叶轮通道间存在着五个失速团,随着时间的推移,五个失速团在不同的通道之间以低于叶轮转频的转动频率在叶轮之间传播。对通道内部监测点的速度波动进行频域分析的结果表明,失速团的旋转频率约为叶轮转频的23.4%,即失速团的旋转角速度为叶轮转速的4.68%。而在0.41Q_0工况下,由于此时造成失速的初始扰动还不足以使失速团相对于叶轮发生转动,离心泵内部出现了"固定失速"的现象。相比于旋转失速,在发生固定失速时,叶道中的阻塞系数波动较小,因此这是一种相对稳定的失速现象。同时,叶轮叶片数对失速的类型有着决定性的影响。Rotating stall is a common unstable flow phenomenon in centrifugal pumps, usually occurring in part-load conditions. It will cause the performance instability of a pump, and even excite the resonance of the whole pump system in certain extreme cases. In this study, stall phenomena in a centrifugal pump under part-load conditions are investigated using CFD method, and the simulated results are compared with experimental measurements, including characteristic curves, internal flow structures, and frequency spectra. A new parameter of the impeller passage, namely blockage coefficient, is adopted to quantitatively evaluate the degree of rotating stall, and the large-scale vortex in a stalled channel is regarded as a stall cell. At the operating flow rate of Q = 0.35 Q0（where Q0 stands for the optional flow rate）, five rotating stall cells are observed in the impeller, which propagate among different impeller channels at a rotating frequency lower than that of the impeller. From frequency spectrum analysis, the dominant frequency of these stall cells is about 23.4% of the impeller rotational frequency, or only 4.7% for each stall cell. At Q = 0.41 Q0, a stationary stall phenomenon is observed in the impeller passages. In this case, the blockage coefficient of each impeller channel varies slightly during impeller rotation, and thus the stall of this type is relatively stable. Furthermore, the number of impeller blades plays a crucial role in determining the type of stall.

关 键 词：离心泵 旋转失速 数值模拟 阻塞系数 固定失速 

分 类 号：TH311[机械工程—机械制造及自动化]