Effect of rotation on heat transfer in two-pass square channels with five different orientations of 45 angled rib turbulators

The effect of various 45 angled rib turbulator arrangements on the Nusselt number ratio in a rotating, two-pass, square channel is investigated for three Reynolds numbers (5000, 10,000, 25,000), with rotation number up to 0.11, and two channel orientations with respect to the axis of rotation ((beta)=90 and 135 ). Five different arrangements of rib turbulators are placed on the leading and trailing surfaces at an angle of +45 or ?45 to the main stream flow. The rib height-to-hydraulic diameter ratio (e/D) is 0.125; the rib pitch-to-height ratio (P/e) is 10; and the inlet coolant-to-wall density ratio ((delta)(rho)/(rho) is maintained around 0.11. The results show that the rotating ribbed surface Nusselt number ratios increase by a factor of 2 compared to the rotating smooth surface results. The results also show that the heat transfer enhancement depends on the ribangle orientation (+45 or ?45 ) to the main stream flow in the first or second pass of the channel for both rotating and nonrotating conditions. Overall, the parallel rib cases show better heat transfer enhancement than the crossed rib case for both rotating and non-rotating conditions. The 90 channel orientation with respect to the axis of rotation produces greater rotating effect on heat transfer over the 135 channel orientation.