旋转对光滑U形通道内换热的影响研究

在通道进口雷诺数从6 100～25 100,旋转数从0～0.26的范围内,实验研究了旋转对光滑U形通道的换热特性的影响.通道长度与水力直径的比值为23,通道平均旋转半径与水力直径的比值为24.结果表明,静止状态下,通道局部努塞尔数随雷诺数增加而增加,但其沿程分布规律基本不变.旋转状态下,第一通道前后缘换热差异随旋转数的增加而增加,在第二通道中正好相反.旋转对第一通道中部转静努塞尔数比的影响最大,而弯道效应则主要影响转弯段及第二通道上游的换热.

Effect of Rotation on Heat Transfer in a Rotating U-Shaped Passage

The influence of rotation on convective heat transfer in a rotating two-pass square channel was investigated experimentally for Reynolds number from 6100 through 25 100 and the rotation number from 0 through 0.26.The square channel has a length-to-hydraulic diameter ratio of 23.The mean rotating radius to the channel hydraulic diameter ratio was kept at a constant value of 24.The results show that the values of Nusselt number reveal an increase with the increase of Reynolds number,keeping the ratios of local Nusselt number to Dittus-Boelter correlation at all locations the same as stationary state.As the channel rotated,the Nusselt number of the first pass was found to increase on the trailing wall and to decrease on the leading wall,the reverse was true in the second pass.The effect of rotation on the heat transfer is most significant in the middle part of the first pass.The geometry of the sharp turn dominates the local heat transfer distributions in the turning region and the upstream of the second pass.