中文摘要：

针对带45°肋片圆形弯头U型通道进行了传热和压力分布特性的实验研究.实验中进口雷诺数变化范围在30 000-55 000之间.研究表明,肋片引起的横向二次流在弯头前区域是强化传热的主要因素.不同雷诺数下传热分布和压力分布的趋势完全一致,但弯头区后半段上传热分布有所差异.通道中的最大压降出现在弯头区,进口雷诺数越大,弯头损失系数和总损失系数都有所减小.流体在圆形弯头中,加速效果没有矩形弯头强烈,弯头区和弯头后的传热较矩形弯头都有较大幅度地减小.

英文摘要：

An experimental investigation was conducted to assess the heat transfer and pressure drop distribution of a two-pass channel with a round turn.The Reynolds numbers investigated varied from 30 000 to 55 000.This demonstrates that the secondary flow induced by ribs is the main factor to enhance the heat transfer before turn region.Under different Reynolds numbers,the trend of heat transfer and pressure drop distribution in the duct is consistent.However,the heat transfer in the after turn region is different.Moreover,the largest pressure drop occurs in the turn region.As the Reynolds number increases,the loss coefficient of the turn and the whole duct will decrease.Compared with two-pass channel with a sharp turn,the heat transfer in the turn region and after turn region in this study is lower,because the acceleration effect in the round turn region is not as strong as that in sharp turn.