基于特征线法模拟全尺寸临界流实验喷放特性

Full-scale critical flow test blowdown performance based on the method of characteristics

为了获取冷却剂丧失事故喷放阶段热工水力参数峰值等关键数,本文使用一维两相流体动力学方程组对失水事故现象进行数值模拟研究。对于喷放物理过程中的强对流带来的非线性特性和耦合特性,使用特征线法对动量方程和能量方程解耦,进而实现控制方程组在瞬态下的离散求解。以Marviken临界流实验为例,同时使用基于特征线法的自编程序和系统分析程序RELAP5进行求解,通过数值模拟的结果和实验数据的对比验证了特征线法的有效性。此外还对喷管的几何尺寸、初始流体状态参数等对喷放特性的影响进行了计算,并给出了相应的变化规律。

To obtain some maximal values of thermal-hydraulic characteristics in the blowdown phase of the loss of coolant accident,the blowdown performance of the discharge process is numerically simulated using one-dimension-al two-phase hydrodynamic equations.For the nonlinear and coupling characteristics caused by severe convection in the physical process of discharge,the momentum equation and energy equation are decoupled by the method of characteristic(MOC).Then,the discrete solution of the control equations in the transient state is discretized and solved.Based on Marviken critical flow tests,the self-coding program and system analysis program RELAP5 are used to solve the equations.The effectiveness of the MOC is verified through a comparison of numerical simulation results and experimental data.In addition,the effects of the nozzle geometry and initial fluid state on the blowdown performance are studied,and the variation curves are obtained.