Application of high-order numerical algorithm for two-fluid two-pressure model: Hydraulic load analysis

Abstract

Hydraulic load analysis is of great importance in the design of pressurized water reactor. It provides load conditions for structural mechanics analysis of primary loop system and ensures the reliability of primary loop pipeline and main equipment. Currently common hydraulic load analysis software mainly includes RELAP5 and WAHA, both of which adopt the classical two-fluid six-equation single pressure model and the first-order differentiation algorithm. The single pressure model is not stable, and its numerical results are prone to oscillation under high-order precision schemes. Meanwhile, the low-order algorithm is not accurate enough, which is not conducive to the simulation of pressure wave problems. However, the two-fluid two-pressure model is unconditionally adaptive. In order to improve the accuracy of the numerical algorithm and ensure the stability of the numerical value, a high-order semi-implicit algorithm for solving the transient term and convection term is developed based on the two-fluid two-pressure model. Finally, the high-order algorithm is applied to the hydraulic load problems such as shock tube, water hammer and blowout. The results show that the algorithm can effectively reduce the numerical diffusion and improve the prediction accuracy.