Channel orientation effect on endwall heat transfer in rotating cooling passages with pin-fins

Abstract

Heat transfer was experimentally measured using a rotating pin-fin channel involving two channel orientations, namely 90 degrees and 150 degrees, with respect to a rotating axis. A rectangular channel with an aspect ratio of 4:1 was selected to study internal cooling near the trailing edge of a turbine blade. A newly developed method of liquid crystal thermography along with stroboscopic photography was used to obtain detailed heat transfer contours on an endwall surface. The pin-fin arrays were designed in either inline or staggered patterns, and the Reynolds number ranged from 5,000 to 20,000. The pressurized air flow acted as the working fluid, and the highest rotation number was thus 0.39. The influence of rotation was greater on the inline array than on the staggered array, engendering higher heat transfer enhancement on the leading and trailing surfaces. Compared with the other orientation, the inclined orientation (150 degrees) engendered a larger spanwise heat transfer variation because of the shifted rotation-induced secondary flows. The inline array exhibited the highest rotation-induced heat transfer enhancement at the 90 degrees orientation, and the highest enhancement levels were 90% and 40% on the trailing and leading surfaces, respectively. (C) 2019 Elsevier Ltd. All rights reserved.