矩形通道内置加热板混合对流的实验研究

Experimental Investigation of Mixed Convection in Rectangular Channel with Attached Flat Heated Plate

通过实验研究了中心截面带有加热平板的水平和倾斜矩形通道入口段的混合对流换热,该矩形通道和加热平板均采用高热导率材料制作,矩形通道外壁面绝热.实验过程中Re从334变化到1 911,管道倾角从-60°增加到60°.实验数据处理时采用壁面均匀恒定热流边界条件,处理结果与相关文献吻合较好.通过实验得到了管内平均Nusselt数和压力损失的分布.实验结果表明:换热系数是充分发展层流混合对流的2到3倍;当Re增加时,管内换热系数增加,压损随之增大;当Re较小时,换热系数和压损均随倾角的增大显著增大;当Re约增加到1 800时,角度变化对换热系数和压损的影响很小.

The flow and heat transfer in a rectangular channel with a fiat heated plate in the middle section was experimentally investigated. The rectangular channel was made of aluminum alloy and thermally adiabatic at all four walls. The heated plate was made of alloy steel and subjected to uniform heat flux. The heat transfer processes in mixed convective air flow through the rectangular channel were under various operating conditions： Pr as 0. 7, Reynolds number ranging from 334 to 1 911, inclination angle ranging from -60° to 60°. Data measured show that all the wall temperatures at the same cross section were almost equal. The boundary condition, constant axial wall heat flux at all the walls, was applied in the data reduction. The experimental results agree well with the data reported in the literature and the reliability of the experimental setup and the data reduction is confirme＆ The results show that the heat transfer coefficient is about two or three times as large as that in the laminar fully developed region. The influence of Reynolds numbers and channel inclinations on the flow and heat transfer was also investigated. The experimental results show that the average Nusselt numbers and pressure drop increase with the increase of the Reynolds number from 334 to about 1 500 and the increase of the inclination angle from -60° to 60°. However, when the Reynolds number bers and pressure drop are independent of the increases to over 1 800, the average Nusselt numinclination angle.