CFD-Based Numerical Study On Hydrodynamic Modeling Of 1000MW Nuclear Reactor Coolant Pumps

Nuclear reactor coolant pump, also called nuclear main pump, is the only rotating equipment in the first circuit of a reactor system. It is used to provide the pressure head for the reactor coolant to drive adequate cycling flow rate through the reactor core.As the key component of nuclear power stations, the nuclear main pump needs to be in long-term operation and of high safety and reliability under a high-temperature, high-pressure and strong-radiation environment. Consequently, strict requirements are put forward in the processes of its design and manufacture.At present in China, the numerical studies of three-dimensional viscous flows in the nuclear main pumps are relatively rare. The design and manufacture of the key components, such as the impeller, volute and other hydraulic components, still entirely rely on imported technologies. Therefore, the study on the nuclear main pump design is of great significance.In this study, a preliminarily exploratory investigation into the hydrodynamic modeling of three-dimensional viscous flows in the nuclear main pump was attempted using CFD approach. Commercial CFD software was employed to conduct three-dimensional simulations and analyze the pros and cons of different designs. Finally, an optimized design was derived from the numerical simulations.As the key part of this study, the impeller design was conducted using a new model-transforming control method. Compared to the approach of traditional velocity factor, this method is more efficient in designing a new nuclear main pump impeller based on an existing high-performance impeller of a similar specific speed. Meanwhile, it coupled the traditional model transforming method with the CFD approach by taking into account of the effects of model coefficients on the efficiency. Hence the new impeller which precisely meets the head requirement can be designed at the premise of the design pressure, temperature, flow rate and speed. A design method of matching guide vanes with the impeller was adopted for guide vanes. By the comparisons of various designs, it was found that the design adopting an inlet parallel to the axial line was of the best performance with ideally controlled vortices in the flow field. Additionally, under the design conditions, the overall efficiency is less affected by the guide vane number.In the design of the volute, the emphasis was placed on the design of the volute outlet and especially on the effects of the volute throat on the internal flow of the volute. It has been demonstrated that the design with an obtuse angle shape at the volute throat delivered the optimal hydraulic efficiency due to the improvement of the flow conditions inside the volute. Finally, by analyzing overall performance curves of the optimized nuclear main pump, the preliminary nuclear main pump hydraulic model was established.