HEAT TRANSFER IN A ROTATING, BLADE-SHAPED, TWO-PASS COOLING CHANNEL WITH VARIOUS 45 DEG RIB TURBULATORS AND A TIP TURNING VANE

This work experimentally studied a rotating, blade-shaped, two-pass cooling channel with various 45 deg rib turbulators and a tip turning vane. The first passage of the cooling channel has an aspect ratio (AR) = 4:1 with the coolant moving radially outward. After a 180 deg blade-shaped tip turn, the coolant flows radially inward into the second passage with an AR = 2:1. The first and second passages are oriented at 50 deg and 105 deg from the rotation direction, respectively. In the tip turn portion, a tip turning vane with an oval cross section connects the midlines of the two passes. Two orientations of 45 deg angled ribs were considered in this work: unusual, and criss-cross. The ribs have a profiled cross section and were placed in-line (P/e = 10, e/H= 0.16) on the leading and trailing surfaces of the channel. Five inlet Reynolds numbers (10,000 to 45,000) and five rotational speeds (0-400 rpm) were considered in this study, with a maximum rotation number of Ro = 0.38 achieved in the first pass. The results showed that the reduction from the turning vane on heat transfer and pressure loss for the 45 deg unusual rib case was the lowest. The overall heat transfer for the criss-cross rib case was slightly increased by the turning vane. For pressure loss, the turning vane provided approximately 8% reduction in the 45 deg criss-cross rib case, which was the highest in the rib cases. The 45 deg criss-cross ribs presented the highest thermal performance with the turning vane.