Heat Transfer in a Rotating Blade-Shaped Two-Pass Channel with a Turning Vane

Abstract

The effect of adding a tip turning vane on the heat transfer and pressure loss of a blade-shaped two-pass cooling channel was experimentally investigated in this work. In the first passage with an aspect ratio (AR) of , the coolant traveled radially outward to a 180 deg blade-shaped turn. After the turn, the coolant flowed radially inward in the second passage with . The cooling channel was positioned such that the first and second passes were angled 50 and 105 deg from the direction of rotation, respectively. The turning vane was designed with an oval cross section to connect the midlines of the two passages. A 45 deg angled ribbed case (inline, ) was studied in addition to the smooth surface case. The Reynolds number ranged from 10,000 to 45,000 in the first pass and 16,000 to 73,000 in the second pass. In this study, five rotational speeds (0–400 rpm) were considered, and the maximum inlet rotation number was . The results showed that the turning vane decreases both heat transfer and pressure loss in the cooling channel. The average overall heat transfer for the entire channel was reduced 6 and 4% by the turning vane in the smooth and ribbed cases, respectively. However, with the presence of the turning vane, the tip wall heat transfer was increased in the range of 10–20% in both the smooth and ribbed cases. The rotational effect on heat transfer was found to be reduced with the presence of the vane. On the other hand, the turning vane provided 10 and 5% pressure loss reductions in the smooth and ribbed cases, respectively.