Uneven Wall Heat Flux Effect on Local Heat Transfer in Rotating Two-Pass Channels With Two Opposite Ribbed Walls

The influence of rotation and uneven heating condition on the local heat transfer coefficient in rotating, two-pass rib-roughened (rib height e/D_H ≈ 0.17 − 0.20; rib pitch p/e = 5) rectangular channels with cross-sectional aspect ratios of 1 and 1.5 were studied for Reynolds numbers from 5000 to 25,000 and rotation numbers from 0 to 0.6152. Regionally averaged Nusselt number variations along the duct have been determined over the trailing and leading surfaces for two pass channels. In general, Coriolis-induced secondary flows are shown to enhance local heat transfer over the trailing (leading) surface in the first (second) pass compared to a duct without rotation. Centrifugal buoyancy is shown to influence the heat transfer response with heat transfer being imposed on both leading and trailing surfaces as the wall-to-bulk fluid temperature difference is increased with other controlling parameters fixed. Results also indicate a slight decrease in heat transfer coefficient for an increase in passage aspect ratio. Results are compared with previous studies. It is found that the results agree quite well with those reported by other works for two-pass flow channels.