带斜孔肋大宽高比矩形通道的强化传热特性

为了获得带斜孔肋大宽高比矩形通道的强化传热特性,并寻求最佳的孔排倾斜角度,调节孔排倾斜角度和通道雷诺数,使其分别在0°~30°和3×104~9×104范围内变化,通过数值计算系统分析了通道摩擦因数和带肋壁努塞尔数等参数的变化规律.研究发现:相比于常规肋片,新型斜孔肋有效改善了肋片后方紧邻肋片的局部区域的壁面换热,并降低通道的摩擦因数,但传热增强因子有所减小;随着孔排倾斜角度的增大,通道的相对摩擦因子单调升高,传热增强因子则呈现出先升高后降低的变化过程,因此存在着最优孔排倾斜角度为15°,此时斜孔肋的强化传热综合指标达到最大值;随着通道雷诺数的增大,斜孔肋通道的摩擦因数小幅减小,换热则逐渐增强. 

Enhanced heat transfer characteristics in a large aspect ratio rectangular channel with inclined perforated rib

The enhanced heat transfer characteristics of inclined perforated rib in a large aspect ratio rectangular passage were studied through numerical simulations. The holes inclination angle and entrance flow Reynolds number were adjusted in the range of 0°-30° and 3×10⁴-9×10⁴ respectively. The variation laws of channel friction factor and its rib-wall Nusselt number with these parameters were system analyzed. The calculation results reveal that the inclined perforated rib has a lower friction factor and an improved local heat transfer immediately downstream from the perforated rib due to the impingement of jet-like flows as compared with the solid rib. With the increasing of holes inclination angle, the relative friction factor is elevated monotonously, and the averaged Nusselt number ratio take on up-down tendency, therefore an optimal holes inclination angle is 15°, when the thermal performance factor reached its maximum. The friction factor slightly decreases and the averaged Nusselt number gradually increases with the increasing of Reynolds number for the inclined perforated rib.