核用屏蔽泵采用与主叶轮同轴旋转的辅叶轮为机组冷却循环提供动力。因辅叶轮是采取在推力盘开孔的结构形式，结构尺寸受到推力盘的限制，其流道设计不仅必须满足机组冷却循环的要求，而且要保证结构强度和加工方便的需要。以某核用屏蔽泵辅叶轮泵为原型进行优化，通过组合4种不同出口安放角和3种不同孔数的辅叶轮，采用基于多工况三维数值模拟的性能预测方法对比分析出口安放角和孔数在变流量工况下对辅叶轮泵性能的影响。结果表明：辅叶轮孔出口安放角的变化会影响辅叶轮泵的性能，适当减小辅叶轮孔的出口安放角能提高辅叶轮泵的扬程和效率，使蜗壳的流动趋于更加稳定，并减小了蜗壳的水力损失；辅叶轮孔数的增加能有效提高辅叶轮泵的扬程。当45°出口安放角与8孔搭配时，辅叶轮泵的性能最佳，扬程比原始方案提高3.2m，效率提升2%。出口安放角及孔数的选择搭配有利于辅叶轮高效稳定运行，为类似屏蔽泵冷却循环系统设计提供指导意义。

The nuclear canned pump uses an auxiliary impeller that rotates coaxially with the main impeller to power the unit"s cooling cycle. Because the auxiliary impeller is adopted in the way of opening the thrust plate, the structural size is limited by the thrust plate. The design of the flow channel must not only meet the requirements of the cooling cycle of the unit, but also meet the needs of structural strength and convenient processing. Optimized by using a nuclear canned pump auxiliary impeller pump as a prototype and used the performance prediction method based on multi-case three-dimensional numerical simulation to compare and analyze the performance of the auxiliary impeller pump with different outlet angle and hole number under variable flow conditions by combining auxiliary impeller with four different outlet angles and three different numbers. The results show that the change of the outlet angle of the auxiliary impeller hole will affect the performance of the auxiliary impeller pump. Appropriately reducing the outlet angle of the auxiliary impeller hole can improve the head and efficiency of the auxiliary impeller pump, and the flow of the volute tends to be more stable. The hydraulic loss of the volute is reduced; Increasing the number of auxiliary impeller holes can effectively increase the head of the auxiliary impeller pump. When the 45° outlet angle is matched with 8 holes, the auxiliary impeller pump has the best performance, the head is 3.2m higher than the original model, and the efficiency is increased by 2%. The selection of the outlet angle and the number of holes is conducive to the efficient and stable operation of the auxiliary impeller, which can provide guiding significance for the design of a similar canned pump cooling cycle system. Key words： canned pump; auxiliary impeller; outlet angle; number of holes; performance characteristics; turbulent kinetic energy

四川省科技计划项目(2017JY0047)