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.