Abstract: A shrouded impeller and its cavities were numerically simulated to investigate the flow field structure in the Impeller Front-side Cavity (IFC) and also the effects of the IFC and its leakage flow on the impeller. It concluded that at design mass flow，compared with the conventional case without including cavities，the pressure ratio remains almost unchanged and the efficiency is reduced by 0.82% in the case including cavities without leakage while the pressure ratio and efficiency in that including cavities with leakage are reduced by 3.7% and 2.4%，respectively. The pressure distribution inside the IFC is of radial equilibrium，and the temperature is higher than that in the main flow. There is a circulation inside the IFC，and considering the air circulation between the IFC and impeller main passage，a dual circulation flow field structure is observed in the shrouded impeller. The leakage flow could increase impeller total axial thrust .At design mass flow，total axial thrust of the case with leakage is 3.17 times of that without leakage.

Key words: Shrouded impeller；Impeller front-side cavity；Axial thrust

摘要： 为研究轮盖空腔内部流场结构，分析轮盖空腔及泄漏流对叶轮的影响，对闭式离心叶轮及其空腔进行了数值模拟计算。结果表明，在设计流量下，与只计算主流道的常规方案相比，加入空腔无泄漏的方案压比基本不变，效率降低了0.82%，加入空腔存在泄漏的方案压比及效率分别降低了3.7%和2.4%。空腔内压力径向平衡，温度高于主流道。轮盖空腔中存在环流，同时空腔中气流和叶轮主流之间又存在环流现象，二者形成独特的双层环流结构。泄漏流会增加叶轮所受总轴向推力，设计流量下存在泄漏时总轴向推力为无泄漏时的3.17倍。

关键词: 闭式叶轮；轮盖空腔；轴向推力