In the operation of a nuclear plant system, a distorted inflow of a reactor coolant pump appears owing to the steam generator channel head and multi-bend, leading to the deterioration of pump performance and stability. In the present study, three-dimensional numerical calculations of three model geometries are carried out using block grid technology, with RNG k-ε and DDES model applied in the steady and transient simulation. The simulation results are validated with an experiment testing the pump with a short inlet pipe. As for the results, under the distorted inflow condition, the pump head and efficiency are reduced by 4% and 5.2% respectively at the nominal flow rate. Additionally, when the pump is coupled with upstream structures, the inlet flow becomes distorted and more chaotic, and the swirl and radial flow are produced by asymmetric pressure difference. Meanwhile, a pair of local vortices appears in the inlet section, forming re-distributed mass flow rates. As the distorted flow enters the pump, the blade inlet pressure and flow rate are unevenly distributed. Moreover, the evolution process of the vortex is accompanied with strong non-uniformity in the impeller channel, and thus asymmetric tangential force is imposed on the blades, increasing the risk of the fatigue breakdown of the impeller.

在核电站系统的运行中，由于蒸汽发生器的通道头和多头弯头，反应堆冷却剂泵的流入出现了扭曲，从而导致了泵性能和稳定性的下降。在本研究中，使用RNGk -ε，使用块网格技术对三个模型几何进行了三维数值计算。 和DDES模型在稳态和瞬态仿真中的应用。仿真结果通过使用短进口管测试泵的实验得到验证。结果表明，在变形的流入条件下，在额定流量下，泵压头和效率分别降低了4％和5.2％。另外，当泵与上游结构连接时，入口流量会变形并且更加混乱，并且涡流和径向流量会由不对称的压差产生。同时，在入口部分出现了一对局部涡流，形成了重新分布的质量流率。当扭曲的流量进入泵时，叶片入口压力和流量分布不均匀。此外，涡旋的演变过程在叶轮通道中伴随着强烈的不均匀性，