蜗壳式混流泵空化工况扬程下降机理  

Head degradation mechanism research on mixed-flow pump under cavitation conditions

作　　者：施伟[1,2] 张大庆[1] 潘中永[1] 李彦军[1] 袁寿其[1] 

机构地区：[1]江苏大学流体机械工程技术研究中心,江苏镇江212013 [2]南水北调东线江苏水源有限责任公司,江苏南京210029

出　　处：《排灌机械工程学报》2013年第10期851-855,共5页Journal of Drainage and Irrigation Machinery Engineering

基　　金：国家自然科学基金资助重点项目(51239005);国家自然科学基金资助项目(51109096)

摘　　要：基于Rayleigh-Plesset方程的空化模型和剪切应力输运湍流模型(SST),应用计算流体动力学技术,对比转数n s为449的蜗壳式混流泵设计工况下的流场进行空化数值模拟分析.根据模拟结果获取了该泵的空化特性曲线,对开始发生空化、临界空化和空化严重3种工况下叶轮内的空化现象进行分析,并找到混流泵空化断裂和扬程下降的原因.数值模拟结果和试验结果一致,误差在5%以内.模拟分析结果表明:流道内的空泡增多到一定程度后会使液体发生边界层分离,产生旋涡,通过叶轮流道内空泡体积分数和叶片背面流线分布图可以看出,旋涡是导致该混流泵空化断裂工况下扬程下降的最主要原因,初步揭示了混流泵内空化流场的分布规律.The cavitating flow in a mixed-flow pump with volute collector( the specific speed n s= 449)under design condition was simulated numerically based on the cavitation model Rayleigh- Plesset equations and the SST turbulence model. The NPSHA- H curve was obtained accordingly. To investigate the inherence of mixed-flow pump cavitation breakdown condition and head degradation,the cavitation phenomenon in the impeller were comparatively analyzed under the inception,critical and severe cavitation conditions. The numerical simulation results and experimental ones were consistent with the error less than 5%. When the cavitation bubble in the flow passage adds up to a certain extent,it will make the liquid boundary layer separation and produce vortexes,which can be observed from the picture of vapor volume fraction distribution in impeller passage and streamline distribution on blade suction side. Vortex is the main cause of the mixed-flow pump cavitation breakdown and head degradation. The regularities of distribution of mixed-flow pump cavitating flow field were revealed.

关 键 词：蜗壳式混流泵 扬程下降 数值模拟 空化 断裂工况 

分 类 号：TH[机械工程]