Heat transfer in two-pass rotating rectangular channels (AR=2 : 1) with discrete ribs

This paper reports the heat transfer coefficients and friction factors in a two-pass rotating rectangular channel with ribs, applicable to an internally cooled turbine blade. The channel aspect ratio is 2:1. Five different turbulators are studied: 45-deg angled ribs, V-shaped ribs, discrete 45-deg angled ribs, discrete V-shaped ribs, and crossed V-shaped ribs. The ribs are placed on the leading and trailing surfaces. The Reynolds number ranges from 5000 to 40,000. The corresponding rotation numbers vary from 0.206 to 0.026 for a fixed rotation speed of 550 rpm. The rib-height-to-hydraulic-diameter ratio (e/D) is 0.094, the rib-pitch-to-height ratio (P/e) is 10, and the inlet-coolant-to-wall-density ratio (/) is maintained around 0.115. For each case, two channel orientations with respect to the plane of rotation are studied, 90 and 135 deg. The results show that the V-shaped ribs and discrete V-shaped ribs have higher heat transfer enhancement than the 45-deg angled ribs and discrete 45-deg angled ribs for both rotating and nonrotating cases. The pressure measurements show the 45-deg angled ribs incurred the highest frictional losses. Based on the present study, the discrete V-shaped ribs have the best overall thermal performance in both rotating and nonrotating channels. Copyright 2006 by the American Institute of Aeronautics and Astronau tics, Inc. All rights reserved.

Heat transfer in two-pass rotating rectangular channels (AR=2 : 1) with discrete ribs Academic Article