3种转角下旋转U形方通道的局部换热

在旋转数为0~0.26内用实验方法研究了转角对旋转U形方截面通道换热特性的影响.3种通道转角分别为0°,22.5°,45°.通道转角的变化引起了通道内哥氏力二次流的变化,继而导致通道各表面换热的变化.结果表明:随通道转角的增大,前缘与后缘之间努塞尔数的差异减小,而内侧面与外侧面之间的努塞尔数差异增大;在低旋转数下,转角的变化对U形通道换热的影响较小,但高旋转数下,转角的变化对U形通道换热的影响变得明显. 

Local heat transfer in a rotating U-shaped square channel with three channel orientations

The influence of channel orientation on the local heat transfer coefficient in a rotating, U-shaped, square channel with smooth walls was investigated for rotation number from 0 to 0.26. The three channel orientations were square channel parallel to the rotation axis, square channel twisted at 22.5° to the rotation axis and square channel twisted at 45° to the rotation axis. A change in the channel orientation about the rotating frame causes a change in the secondary flow structure,consequently, the heat transfer coefficient from the individual surfaces of the channel changes. Results show that the Nusselt number difference between leading and trailing surfaces was reduced as the channel twisted to the rotation axis, however, the inner and outer surfaces show an increase in Nusselt number discrepancy over their corresponding parallel channel orientation values. Effect of channel orientation on heat transfer is relatively prominent for high rotation number.