Numerical investigation on the melting behavior mechanism of fuel rod using MPS-CV method

The Moving Particle Semi-implicit (MPS) method, which is a particle method without grid meshes, is a fully Lagrangian method for incompressible flows. It has advantages in describing fluid interface with large deformation and phase transition problems. However, the Laplacian model presented in the original MPS method would overestimate the results of heat transfer when applied to an energy equation. In this paper, MPS-CV (CV is the abbreviation of Control Volume) method, a particle-grid hybrid method based on MPS method and Finite Volume Method (FVM) was developed to solve the convective heat transfer problems exactly. In this method, the momentum conservation equation was solved by MPS method and the energy conservation equation was solved by FVM. Some verification examples, such as one dimensional heat penetration problems under different conditions were carried out to verify the effectiveness of the new method. The simulation results by the MPS-CV method were compared with the results by the original MPS method and the exact solutions. Compared with the original MPS method, the MPS-CV method has high simulation accuracy in simulating heat transfer problems. The results also indicate that the deficiencies of overestimating thermal conduction and inaccurate calculation of boundary temperature in the original MPS method were solved using the MPS-CV method. In this paper, the melting behavior of nuclear reactor fuel rod at high temperature is studied using the MPS-CV method. A phase change model of melting point with particle composition was developed. The melting behaviors of the cladding of two different layout methods were analyzed. The formation of local molten pool and the phenomenon of broken candle drop were observed from the simulation results. (author)