变频给水泵小流量并联运行发生汽蚀的分析

The Cavitation Analysis for Parallel Operation of Converter Pump with Small Flow

白城市某电厂母管制给水系统并联运行的给水泵,其中一台变频泵运行时发生了汽蚀。一般来讲,多级泵只在首级发生汽蚀,但是该变频泵的后几级同样发生了汽蚀。由于后几级压力远高于水的汽化压力,给水泵后几级的汽蚀,从压力降低到汽化压力的角度无法解释发生汽蚀的原因。当调节范围过大时,水泵只有小物流量输出甚至无流量。针对这种情况,使用CFD软件Fluent对变频泵内部流场进行模拟,模拟水泵在小流量运行时,水泵流道内局部速度场的分布,分析流道内是否有漩涡存在。研究流场的速度变化以及水泵导叶内的漩涡分布情况,分析漩涡产生的汽蚀的分布。

The parallel operation of converter pump and general pump on header feed-water system which is used in a power plant in Baicheng Jilin,cavitations occurred in converter pump. Generally,cavitations occurred only in first-stage of multi-stage centrifugal pump,but the cavitations occurred in secondary stages of the con-verter pump. The pressure in the secondary stages is much higher than the vapor pressure. For this reason,from the point of view of pressure reduce we can’ t explain why cavitations occurred. When the adjustment range is too large,then the pump output only a small flow or even no flow. To address this situation,a CFD software Flu-ent has been developed to simulate the three dimensional flow field inside convert pump in this article. When the pump runs in a small flow,it simulated the velocity distribution of the convert pump and research whether swirls exists in the flow channel of the pump. It researched velocity changes of the flow and the swirl distribu-tion in the impellor. Then study the distribution of the cavitations which were caused by swirl.