压水堆四通道模型全高度上的单相流数值模拟

Numerical simulation of single-phase flow in a PWR four-subchannel model with overall length

为了研究压水堆芯在全高度上的单相热工水力为特性,基于曙光高性能大型并行计算集群,对压水堆中包含7个带搅混翼、刚凸及简化弹簧的完整定位格架的四通道模型在全轴向高度上进行了数值模拟.数值计算基于稳态RANS控制方程组,雷诺应力项的封闭采用RNG k-ε模型,方程各项的空间离散均采用相应的二阶格式,可同时保证计算效率和计算精度.数值结果展现了通道及格架内的流场和温度场,得到了截面平均温度、压力、二次流强度及Nu的轴向变化规律.分析表明,格架下游换热效率及温度非均匀度主要受二次流的影响,受湍流脉动的影响相对较小,且不同定位格架下游二次流强度变化趋势基本一致.

In order to study the thermal-hydraulic performance of the pressurized water reactor（PWR） core in overall length,a computational fluid dynamics（CFD） simulation for a four-subchannel model under single-phase flow condition was conducted by utilizing the Sugon high performance parallel computing cluster.The four-subchannel model included seven integrated spacer grids which consist of straps,mixing vanes,dimples and simplified springs.The steady-state Reynolds-averaged Navier-Stokes（RANS） equations and renormalization group（RNG） k-ε turbulence model were solved to improve computational efficiency and the second-order upwind discretization schemes for the convective terms in equations were employed for improving computational accuracy.The numerical simulation results well show the flow field and temperature field in the subchannels.The changing rules of the pressure,temperature,secondary flow intensity and Nu along overall axial length were determined.Analysis show that the heat transfers efficiency and thermal non-uniformity downstream of spacer grids were mostly affected by secondary flow and the influence of turbulence pulsation on them was comparatively less.Moreover,the variation trend of secondary flow intensity downstream of different spacer grids was basically consistent.