水平六角蜂窝腔内三维自然对流的数值计算

Numerical Simulation of Natural Convection in Horizontal Hexagonal Honeycomb

通过对水平六角蜂窝腔内流动和换热的数值计算,得到了Ra数从500～105内侧壁绝热时蜂窝腔内空气的流动换热结果.计算对比分析了在大温差条件下采用Boussinesq假设所带来的计算误差.数值计算方法采用有限体积的SIMPLEC算法,考虑蜂窝腔内空气物性随温度的变化.计算结果显示,在Ra=1000时,腔内的空气开始出现不稳定.对流项的离散采用二阶迎风格式和QUICK格式可得到几乎相同的结果,而采用一阶迎风格式可使结果产生一定的误差.计算结果也表明,在所计算的问题中,如果采用Boussinesq假设将使计算结果误差比较大.

The numerical study on natural convection in a horizontal hexagonal honeycomb enclosure was performed, and the results of flow and heat transfer were obtained on adiabatic side wall for Rayleigh numbers in the range of 500 to 105. The finite volume method with SIMPLEC algorithm was used in numerical calculation, and the temperature dependency of the fluid properties was considered. The numerical results show that the air in a closed cavity becomes unsteady at Ra=1000. The second order upwind scheme and QUICK scheme give almost the same results of flow and heat transfer in the honeycomb, while one order upwind scheme will result in some error. The numerical results also show that the Boussinesq approximation will bring large error for big wall temperature difference.