Effect of Pumping Chamber Outlet Contraction Angle on Hydraulic Performance of Main Nuclear Reactor Pump

An RCP（reactor coolant pump） impeller and diffuser are designed to meet the hydraulic performance needs of the nuclear reactor coolant pump in a domestic 1000MW nuclear power plant.In order to study the effect of the pumping chamber outlet contraction angle,13 kinds of are designed and Pro/E is utilized for three-dimensional design,and CFD code Fluent is utilized for numerical simulation.Finally,the internal velocity vector and streamline of the RCP are obtained.It is revealed that the contraction angle has a significant effect on the connection area between pumping chamber and outlet.As is between 12° and 16°,and the efficiency of the RCP is above 70%.When is 15°,the efficiency reaches to the maximum 74.2%.When is 15° and other parameters unchanged,the reverse flow region of the impeller inlet and diffuser outlet becomes larger with the decrease of the flow rates.When the flow increases,the reverse region approaches closer to the impeller inlet.Reverse flow is the main cause of the pressure fluctuation of the connection area between pumping chamber and outlet,and the farther away the design point,the more serious the pressure fluctuation.