环形通道内空气湍流正在发展流与壁面辐射的耦合换热研究

COUPLED HEAT TRANSFER OF TURBULENT DEVELOPING AIRFLOW WITH WALL RADIATION INANNULAR CHANNELS

对内环壁面加热、外环壁面绝热的圆环型通道,数值研究了空气湍流正在发展流与壁面辐射的稳态耦合换热。采用低雷诺数k-ε模型与SIMPLEC算法求解气流的湍流流动与对流换热,采用蒙特卡罗法求解壁面间的辐射换热,对流换热与表面间辐射换热通过绝热壁面边界条件进行耦合。通过模拟计算,分析了相关参数及物性变化的影响。研究结果表明,入口Re数与壁面发射率均对通道内的换热有重要影响;考虑空气物性变化与否所预测到的对流热流分布形态相差非常大,常物性下的模拟结果会导致对通道内热输运特性的不正确认识。

The steady state coupled heat transfer of turbulent developing airflow with wall radiation was investigated numerically, which took place in the annular channel with a hot inner wall and an adiabatic outer wall. The low Re ynolds number κ-ε turbulence model and the SIMPLEC algorithm were used to simulate the flow and convective heat transfer, and the Monte Carlo method was employed to solve the radiative heat exchange between walls. The two heat transfer modes of convection and wall radiation interacted by means of the adiabatic boundary condition of outer wall. The effects of relevant parameters and the variable physical properties of airflow were analyzed. The results showed significant effects of the inlet Reynolds number and the wall emissivities. The predicted results of convective heat flux distributions showed great differenee during considering the variable physical properties or not. The numerical results with constant physical proerty assumptions can result in the incorrect recognition on the of heat transport characteristics in annular channels.