Heat Transfer in a Rotating, BladeShaped, TwoPass Cooling Channel With Various 45Deg Rib Turbulators and a Tip Turning Vane

Abstract

This work experimentally studied a rotating, bladeshaped, twopass cooling channel with various 45deg rib turbulators and a tipturning vane. The first passage of the cooling channel has an aspect ratio (AR) = 4:1 with the coolant moving radially outward. After a 180deg bladeshaped 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 tipturn portion, a tipturning 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 crisscross. The ribs have a profiled cross section and were placed inline (P/e = 10, e/H = 0.16) on the leading and trailing surfaces of the channel. Five inlet Reynolds numbers (10,000–45,000) 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 effect of the turning vane on heat transfer and pressure loss for the 45deg unusual rib case was insignificant. The overall heat transfer for the crisscross rib case was slightly increased by the turning vane. For pressure loss, the turning vane provided approximately an 8% reduction in the 45deg crisscross rib case, which was the highest in the rib cases. The 45deg crisscross ribs presented the highest thermal performance with the turning vane.