温度分布对自由盘层流换热的影响

在盘面过余温度为半径的多项式分布的第1类热边界条件下,对自由盘不可压层流流动和换热进行了数值模拟,盘面局部努赛尔数的计算值与理论解相比符合很好。计算结果表明:过余温度成倍变化时,盘面局部努赛尔数不受影响;过余温度按n次单项式分布时,盘面的局部努赛尔数与所有按n次多项式分布时所得局部努赛尔数相比为最大;过余温度为任意多项式分布时,盘面局部努赛尔数数值上介于过余温度单独按该多项式的最高次和最低次分布所得到的局部努赛尔数之间,且随最高次项系数的增大而增大、随最低次项系数的增大而减小、随着中间次数项的系数在低半径区域增大而增大在高半径区域增大而减小。通过对计算数据的分析,给出和验证了过余温度按任意多项式分布时盘面局部努赛尔数的计算公式。

Effect of Temperature Distribution on Laminar Heat Transfer for Free Disk

With First heat boundary condition that polynomial distribution taking disk surface surplus temperature as radius, the numerical simulation of flow and heat transfer for the free disk incompressible laminar was conducted. The calculation of disk Nusselt number well conformed to its theory solution. The results show that the disk surface Nusselt number is constant when surplus temperature change in multiple, is maximumt among all the local Nusselt number obtained according to polynomial distribution with exponent n when surplus temperature is distributed on monomial expression with exponent n, is between the local Nusselt number obtained according to polynomial distribution with maximum and minmuw exponents, and increases with maximum exponent coefficient, decreases with the minimum exponent coefficient, and increases with intermediate exponent coefficient at low radiu regains, decreases with the intermediate exponent coefficient at high radiu regains. Bying analyzing calculateion, the formula for calculating disk surface local Nusselt number with surplus temperature is distributed on any polynominal are presented and validate.