Numerical investigation of erosion and heat transfer characteristics of molten jet impinging onto solid plate with MPS-LES method

Erosion of solid structure and lower head vessel wall by molten jet impingement is a common and important phenomenon in nuclear reactor severe accident. In the present study, a numerical simulation platform was constructed using MPS method with large eddy simulation, and was validated against the experiments that were performed using molten NaCl and Tin as the impingement jet, respectively, and using Tin plate as the target structure. The simulated time-dependent erosion depth agreed well with the experimental data, and the detailed configurations of the crust and molten film formed at the interface of molten jet and plate were reproduced. Furthermore, a parametric study of the effects of molten jet velocity, diameter and temperature on the erosion behavior and heat transfer characteristics was carried out. The results showed that the erosion depth increased as the increase of molten jet velocity, but when the jet velocity was too small, the melt pool formed in the eroded cavity could delay the erosion significantly. The molten jet with a large diameter delayed the erosion due to the thick melt layer in the eroded cavity. The high molten jet temperature resulted in a fast erosion of plate, but the existence of crust in NaCl-Tin delayed the erosion compared with Tin-Tin where no crust formed. Heat transfer coefficient at the eroded plate surface decreased as the erosion depth increasing, due to the development of crust and molten film. It increased with the increase of molten jet velocity and temperature, but decreased as the increase of molten jet diameter. (C) 2016 Elsevier Ltd. All rights reserved.