本文模拟研究了变物性空气在多种正多边形和圆形通道内的湍流流动和换热特性.选用标准κ-ε湍流模型以及SIMPLE算法对此三维椭圆型问题进行求解.模拟结果表明:对于正多边形截面通道,角区的换热要明显弱于非角区区域,且恶化程度随着角区角度的减小而加剧,同时,角区角度越小,管壁的周向换热系数分布越不均匀;正多边形通道与圆形通道平均换热Nu的差异随着正多边形边数的增多而减小;借助当量直径,使用针对圆形通道的湍流换热关联式计算非圆截面通道内的换热将会带来较大误差,对于正多边形通道,这种最大误差存在于正三角形通道与圆形通道之间,误差可达27.5％.
Turbulent flow and heat transfer of air with variable properties in a set of regular polygonal ducts and circular tube have been numerically sinulated.The standard κ-ε turbulence model and SIMPLE algorithm were applied to solve the three-dimensional and fully elliptic problem.The simulation results indicated that for the regular polygonal ducts,the local heat transfer coefficient along the circumferential direction is non-uniform,there is an appreciable reduction in the corner region and the smaller the angle of the corner region,the more appreciable deterioration the corner region causes.The differences between the average Nusselt numbers for the regular ducts and circular tube increase with the decreasing number of sides of the regular polygon.Additionally,the use of hydraulic diameter for noncircular ducts such as equilateral triangular duct will result in unacceptably large errors,on the order of 27.5％,in turbulent heat transfer Nusselt number determined from the circular tube correlations.
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