Comparison Analysis on the Hydraulic Performance and Flow Characteristics on a Reactor Coolant Pump Under Rated Operating Condition Between Lead–Bismuth Eutectic and Water Mediums

Advanced Generation IV nuclear reactors aim to enhance the sustainability, passive safety, reliability, and economic efficiency of reactor operations. Within that, the reactor coolant pump is a critical component in the reactor's cooling system, due to the unique characteristics of the transported medium, posing challenges for engineering applications. This study focuses on a mixed-flow nuclear reactor coolant pump, indicating that significant differences in hydraulic performance and flow characteristics arise due to the varying flow Reynolds numbers under identical operating conditions for the two mediums. Research employing quantitative analysis of boundary layer friction losses and flow separation-induced flow blockage elucidates the origins of hydraulic performance differences. Subsequent studies focusing on the flow characteristics within the impeller reveal that, while the flow patterns inside the impeller show no fundamental differences, an increase in Reynolds number intensifies flow slippage phenomenon, partially diminishing the impeller's work capability. Analysis in static components indicates that the stronger centrifugal forces lead to increased nonuniformity in flow distribution within the guide vanes and an amplified wake phenomenon within the outlet pipe.