Research on influence of wear ring clearance on energy loss of reactor coolant pump

Reactor coolant pump (RCP), the only rotating equipment in the nuclear island, directly determines the safety of the nuclear power system, has been likened to the “heart” of a nuclear power plant. The RCP needs to have very high reliability and stability. Its independent design and construction have always been the focus and difficulty of promoting the independent construction of nuclear power. To study the effect of the wear ring clearance on the energy loss characteristics of the RCP, the numerical simulation of the internal flow field of computation models with different wear ring clearance dimensions were conducted. The results indicate: As the wear ring clearance increases, the trend of performance reduction becomes more significant, especially under the large flow conditions; The increase of the wear ring clearance results in an increase of the pressure loss in the impeller and diffuser, and the variation in pressure distribution in different flow passages under different wear ring clearance dimensions is influenced by the position of the blade; The distribution of turbulent dissipation entropy production rate corresponds significantly to the distribution of direct dissipation entropy production rate, and the dissipation entropy production being more significantly affected by the wear ring clearance dimension closer to the shroud; The change of wear ring clearance dimension has limited impact on the wall shear stress entropy production of the impeller blade, while its effect on the diffuser blade is more pronounced; With the increase of the wear ring clearance, the scale of vortices near the impeller front shroud significantly increases, and the entropy production on the surface of vortex core at the impeller inlet gradually increases. This study is of great significance to ensure the secure and stable operation of the RCP, and provides an important reference for the hydraulic optimization design of the RCP.