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.

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二流体二压模型高阶数值算法的应用：水力载荷分析

摘要 水力载荷分析在压水堆设计中具有重要意义。为一回路系统结构力学分析提供载荷条件，保证一回路管道及主要设备的可靠性。目前常见的水力载荷分析软件主要有RELAP5和WAHA，两者均采用经典的双流体六方程单压力模型和一阶微分算法。单一压力模型不稳定，其数值结果在高阶精度方案下容易出现振荡。同时，低阶算法不够准确，不利于压力波问题的模拟。但是，二流体二压模型是无条件自适应的。为提高数值算法的精度，保证数值的稳定性，基于二流体二压模型，开发了求解瞬态项和对流项的高阶半隐式算法。最后，将高阶算法应用于冲击管、水锤、井喷等水力载荷问题。结果表明，该算法能有效降低数值扩散，提高预测精度。