高温差下卷吸作用对冲击射流换热影响数值研究

Numerical Analysis of Entrainment Effects on Impingement Heat Transfer at High Temperature Difference

基于V2F湍流模型计算研究了卷吸作用对高温差下圆管冲击射流换热的影响,首先通过计算结果与实验值的对比验证模型方法的有效性,然后分析了基于绝热壁面温度计算的努赛尔数和射流有效度随射流和环境的温差以及雷诺数的变化,并研究了取不同定性温度对计算结果的影响。计算结果表明,高温差下定性温度取为射流温度时,基于绝热壁面温度计算的努赛尔数与射流和环境之间的温差近似无关,有效度也与雷诺数无关,但有效度随射流和环境的温差变化较大。因此,在温差较低时,依据射流和环境温度相同时的换热工况得到射流和环境温度不同时的换热工况是可行的,但温差越大,由该方法带来的误差也越大。

Entrainment effects on heat transfer from a round gasjet to a flat wall at high temperature difference were investigated with V2 F model.The modelwas validated against available experimental data sets.The heat transfer coefficient was defined in terms of the difference between the heated wall temperature and the adiabatic wall temperature.The changes of local Nusselt number and the effectiveness with Reynolds number and the temperature difference between jet and environmentwere studied.A dditionally,the influence of different kinds of qualitative temperature was analyzed.A ccording to the results,the Nusselt number changes little with the temperature difference between jeit and environm ent,and the effectiveness is independent of Reynolds num ber,but the effectiveness varies relatively large with the temperature difference between jetand environm ent So it is acceptable to use heat transfer data from unheated jets for the heated jets if the temperature difference is not too high,while corresponding deviation becomes larger with the increase of the temperature difference.