有凸出离散热源封闭空腔内耦合自然对流换热

Conjugate Natural Convective Heat Transfer in an Enclosure with Discrete Protruded Heat Sources

建立了一侧竖壁等温冷却、另一侧竖壁均匀分布五个凸出热源的二维封闭空腔内自然对流换热的数学模型 ,对不同高宽比下的层流自然对流换热进行了数值分析。空腔高宽比范围为 :3.0≤A≤ 12 .2 2 ,RaH 为 10 7,Pr数取 30。计算结果表明 ,与平面热源的情形相比 ,凸出热源的整体换热效果较好。当高宽比A较大时 ,空腔内出现的多个二次流强化了传热 ;A减小时 ,由于二次流的减弱和消失 ,换热效果下降。最后根据计算结果整理出了空腔内的传热关联式。

The mathematic model on natural convection is proposed in a two-dimensional enclosure cavity with an isothermal heat sink at one vertical wall and five discrete protruded sources. Numerical study is performed to analyze the natural convection in the enclosure with a variety of aspect ratio, the range of which is from 3.0 to 12.22, Ra H is 10 7 and Pr is 30.The computed results show that the total heat transfer effect under the situation with discrete protruded heat sources is prior to that with flat wall heated. Moreover, when the aspect ratio is comparatively large, there is several secondary flow in the enclosure, which enhance the convective heat transfer. On the contrary, when the aspect ratio is small, the secondary flow weakened or disappeared, and the total convective heat transfer drop. Finally, the convective heat transfer criteria in the enclosure is obtained.