加力燃油泵隔舌倒圆抑制分离的数值模拟

采用动态亚格子应力模型对加力燃油泵内非定常流场进行大涡模拟,探讨了原隔舌空蚀机理,并研究了不同倒圆半径下泵隔舌附近的瞬时流动规律及流量扬程特性.计算结果表明：小流量工况原隔舌处分离产生的强剪切涡会诱发空化,涡脱落形成的分离再附位置与空蚀破坏核心区域相符;小流量工况下,隔舌倒圆在扩散管内形成转向涡,消除了隔舌壁面分离绕流及附着剪切涡,4mm倒圆半径可以避免空化;设计流量范围内隔舌倒圆提高了泵出口扬程,流量越小扬程增幅越大,小流量工况时扬程增幅达3%.

Numerical simulation on separation control by filleting casing tongue of after-burning fuel pump

Unsteady flow field inside an after-burning fuel pump was investigated by large eddy simulation method with the dynamic subgrid-scale stress model.The cavitation erosion mechanism of the original casing tongue was discussed, and then, the characteristics of transient flow around the casing tongue and pump performance were investigated under different filleting radius conditions.The results show that the flow separation at the original tongue under small flow-rate condition brings strong shearing vortex which induces cavitation.The separation attachment location formed by the vortex shedding agrees well with the real cavitation damage core region.Under small flow-rate condition, tongue filleting results in diversion vortex in the diffuser tube, which suppresses the flow separation around the tongue face as well as the attached shearing vortex, while the 4mm filleting radius case can avoid tongue cavitation.Within the design flow-rate, tongue filleting raises the pump head, and the smaller the flow-rate, the larger the head increase amplitude, which reaches 3% under small flow-rate condition.