低比转数离心泵驼峰工况附近内部流动特性分析  

Analysis of inner flow characteristics in low specific speed centrifugal pump around hump conditions

作　　者：冒杰云[1] 袁寿其[1] 张金凤[1] 李亚林[1] 王业芳[1] 

机构地区：[1]江苏大学国家水泵及系统工程技术研究中心,江苏镇江212013

出　　处：《排灌机械工程学报》2015年第4期283-289,共7页Journal of Drainage and Irrigation Machinery Engineering

基　　金："十二五"国家科技支撑计划项目(2011BAF14B04);国家自然科学基金资助项目(51009072);江苏高校优势学科建设工程资助项目

摘　　要：为了揭示驼峰的产生机理,采用CFD数值预报对低比转数离心泵驼峰工况附近内部流动特性进行了深入分析,建立了扬程与内部流动特性之间的关系.在0.1~1.6倍设计流量下扬程的模拟值与试验值的相对误差在3.62%以内,且预报驼峰所在工况与实测结果基本一致.对驼峰附近工况0.2,0.3,0.4倍设计流量下的内部流动进行了分析,预报结果表明：泵进口管道存在大量回流,造成叶轮进口预旋,诱发驼峰;各叶轮流道内均存在不同程度大小的旋涡,在0.2和0.3倍工况甚至堵塞了整个流道;存在旋涡的叶轮流道出口相对速度值较大,而绝对速度值较小.结合泵基本方程进一步分析,发现出口相对流速的增大使得扬程降低,引发驼峰.对比叶轮出口R/R2=0.9处绝对速度,小流量下波动更加严重,且其圆周分量下降非常明显,直接降低了这些工况下的扬程值;叶轮进口的预旋及出口回流是诱发驼峰的原因,消除或者减小这些非稳态现象可作为抑制驼峰的出发点.To investigate the mechanism of hump,the inner flow characteristics of a low-specific centrifugal pump around hump conditions were analyzed using CFD simulation method and the relationship between head and inner flow distribution was established.The relative error was below 3.62% at 0.1- 0.6 times of the designed flow rate.The flow rate from the simulation that the hump occurred agreed with the test very well.By analyzing the inner flow at 0.2,0.3 and 0.4 times of the designed flow rate,results show that a large amount of backflow could be found in the inlet channel and caused the pre-swirl before the pump inlet which induced hump further.The vortices appeared in all impeller passages of all kinds of sides.At 0.2 and 0.3 times of the designed flow rate,the vortices even choked the passages,disturbing the normal flow.The relative velocity was large at outlet of the passages with vor-tices,while the absolute velocity was very small.It caused the decrease of the head and even the hump when analyzing from the pump basic equation.By comparing the absolute velocity of impeller outlet at R / R2= 0.9 with other flow rates,it could be found that at the three flow rates the velocity fluctuated more seriously and the circumferential component decreased more obviously,inducing the decrease of head.The pre-swirl at impeller inlet and the backflow at impeller outlet are the reasons for hump,so eliminating or restraining these unsteady phenomenon could be the starting point of restraining the hump.

关 键 词：离心泵 低比转数 驼峰 小流量 回流 

分 类 号：S277.9[农业科学—农业水土工程] TH311[农业科学—农业工程]