Coolant flow in rotating internal serpentine channels is highly complex due to the effects of the Coriolis force and centrifugal buoyancy. Detailed knowledge of the heat transfer over a surface will greatly enhance the blade designers’ ability to predict hot spots so coolant may be distributed effectively. The present study uses a novel transient liquid crystal technique to measure heat transfer on a rotating two-pass channel surface with chilled inlet air. The present study examines the differences in heat transfer distributions on channel surfaces with smooth walls, 90 deg rib and W-shaped rib turbulated walls. The test section is made up of two passes to model radially inward and outward flows. To account for centrifugal buoyancy, cold air is passed through a room temperature test section. This ensures that buoyancy is acting in a similar direction to real turbine blades. The inlet coolant-to-wall density ratio is fixed at 0.08, Re = 16,000, and Ro = 0.08. The present study shows that the W-shaped ribs enhance heat transfer in all cases (stationary and rotating) approximately 1.75 times more than the 90 deg ribs. The W-shaped rib channel is least affected by rotation, which may be due to the complex nature of the secondary flow generated by the geometry. A higher pressure drop is associated with the W-shaped ribs than the 90 deg ribs, however, the overall thermal-hydraulic performance of the W-shaped ribs still exceeds that set by the 90 deg ribs.

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