Analysis of Energy Loss Characteristics in an Axial-Flow Reactor Coolant Pump Based on Entropy Production Theory

As the critical component of a nuclear power plant (NPP), the reactor coolant pump (RCP) will suffer energy losses during operation, which can lead to a series of safety issues and adversely affect the efficiency and stability of the NPP. In this study, the SST k-ω turbulence model is utilized to simulate the internal flow field of an axial-flow reactor coolant pump (RCP) under operating conditions of 0.8QN to 1.2QN. Combined with entropy production theory, the distribution characteristics and hydraulic causes of energy loss within different regions of the RCP are revealed. The research findings are as follows: the total entropy production in the RCP first decreases and then increases during operation; with turbulent entropy production consistently accounting for over 70% of the total, and direct entropy production accounting for less than 10%. The impeller and annular casing are always the main components responsible for hydraulic losses within the pump. As the flow rate increases, the total entropy production in the impeller initially decreases and then increases, accounting for between 34.3% and 51% of the total; with energy losses mainly concentrated on the suction side of the impeller blades. The total entropy production in the annular casing gradually increases under operating conditions ranging from 0.8QN to 1.2QN, accounting for between 20.4% and 50.3% of the total. Rotor-stator interaction (RSI), backflow, and flow separation near the volute tongue are significant causes of energy losses within the annular casing. Optimizing the geometric parameters of the impeller and annular casing is an effective way to reduce flow losses in axial-flow RCPs. The research results can provide a reference for the development of optimization techniques for RCPs.