摘要
为研究斜流泵出现的鞍形曲线机理,利用数值模拟的方法对斜流泵进行了研究。通过定常数值模拟得到了鞍形曲线组成部分——扬程骤降段和随后扬程小幅上升段两部分机理。小流量下叶轮轮缘处存在流动分离,并且形成漩涡,导致叶轮出口有效外径的减小,是扬程骤降主要原因。流量继续下降,在叶轮出口靠近轮毂处出现一个大尺度的涡,由于漩涡阻塞作用,导致液流由轮毂向轮缘处偏移,使叶轮内部流态由斜流式转变为离心式,是扬程小幅上升的原因。为研究叶轮出口出现回流的原因,利用非定常数值模拟对导叶进行研究,发现导叶进口处存在失速是斜流式叶轮内部流态转变为离心式的主要原因。同时发现在小流量下导叶进口压力不均匀性是失速核沿圆周方向传播的主要原因。
CFD was used to study the mechanism of the performance curve instability of the mixed flow pump with vane diffuser characterized by the positive slop of the head-flow curve.The two parts of performance curve instability including the dramatically head drop and a slightly rise of the head when the flow rates decreased further.The reason of the two parts was that the decreasing of the effective diameter of the impeller blade TE was caused by the appearance of the vortices in the tip of the impeller outlet which was caused by the reverse flow.The flow separation and the flow pattern of the tested pump shifted to the centrifugal pump which led to the strong vortices in the impeller hub respectively and it was got by steady simulation.The unsteady simulation was used to study the reason of reverse at hub of impeller outlet and it was found that the stall is the main reason for the mixed flow pump shifting to the centrifugal pump.It was also found that asymmetry of pressure at vane inlet is the main reason of the stall for its propagation.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2012年第5期64-68,共5页
Transactions of the Chinese Society for Agricultural Machinery
基金
江苏省自然科学基金创新学者攀登资助项目(BK2009006)
关键词
斜流泵
鞍形曲线
旋转失速
Mixed flow pump
Performance curve instability
Rotating stall
