叶顶间隙对轴流泵轮缘泄漏流动影响的大涡模拟  

Investigation of the effects of tip-gap size on the tip-leakage flow in an axial-flow pump using LES

作　　者：黎耀军[1] 沈金峰[1] 严海军[1] 张志民[2] 

机构地区：[1]中国农业大学水利与土木工程学院,北京100083 [2]中国水利水电科学研究院,北京100038

出　　处：《水利学报》2014年第2期235-242,共8页Journal of Hydraulic Engineering

基　　金：国家自然科学基金资助项目(51009138)

摘　　要：为揭示不同尺寸叶顶间隙下轴流泵轮缘区湍流特征,采用大涡模拟方法对轴流泵在设计流量下的内部非定常流动进行了数值计算,分析了5种叶顶间隙下泵轮缘间隙区的流场结构。通过泵外特性参数预测值与实验结果的对比,证实本文所提出的方法可较准确反映泵内流动特征。结果表明:随轮缘间隙增加,泵扬程、功率和效率均呈下降趋势;叶顶间隙内泄漏流速度沿径向逐渐增大;随间隙尺寸增加,轮缘间隙主泄漏涡强度及与叶片夹角均增大,泄漏涡的非稳定性增强;当间隙δ/D2大于1.0‰,间隙主泄漏涡发展至相邻叶片正面;当δ/D2大于1.5‰,叶顶间隙内出现间隙分离涡,间隙区形成多个次泄漏涡,其影响范围随间隙尺寸的增加而增大。Computational analysis of the flows in an axial-flow pump at design flow rate using large eddy simulation were conducted for five different tip-gap sizes, with the aim to give a better understanding of the effects of the tip-gap size on the tip leakage flow structure. The feasibility of the adopted method in this study was validated by the good agreement between the predicted pump performance and the experimen-tal data. The results indicate that the head, shaft power and efficiency of the pump are decreased as the tip-gap size increases. The velocity of the tip-leakage flow in the tip-gap increased gradually along radial direction. The intensity of the dominant TLV and the angle between the TLV and the blade are found to augment as the tip-gap size increases. When the tip-gap size is larger than 1.0‰D2,the dominant tip-leak-age vortex extended to the pressure side of the neighboring blade. It is also found that the tip-separation vortex and several secondary TLVs were formed in the tip-gap region when the tip-gap size is more than 1.5‰D2,and the range of influence of the TLVs increased with increasing tip-gap size.

关 键 词：轴流泵 大涡模拟 轮缘间隙 间隙泄漏涡 

分 类 号：TV136[水利工程—水力学及河流动力学]