Local heat transfer distribution in a triangular channel with smooth walls and staggered ejection holes

Abstract

Transient liquid crystal experiments have been conducted to determine the distribution of the local heat transfer coefficient in a triangular channel with smooth wails and ejection holes along one or two of the wails. The end of the test channel is either closed or open. The test channel models the leading edge cooling channel in a turbine airfoil with film cooling holes. Results are obtained for Reynolds numbers of approximately 7,500, 15,000, and 30,000. Flow through ejection holes significantly increases the local heat transfer near the ejection holes, especially in the regions immediately downstream of the holes. The maximum heat transfer enhancement on the wall with ejection holes is found in the closed-end channel with ejection holes along one wall only. In the open-end channel, the main flow dominates converging flow toward ejection holes resulting in relatively lower heat transfer on the wall (or wails) with ejection holes. Over the range of the Reynolds number studied, the trends of the heat transfer distributions on the wall (or one of the wails) with ejection holes are relatively independent of the Reynolds number. The velocity gelds that are obtained with a control-volume-based finite difference computer program accompany the experimental results to help better understand how the flows affect the local heat transfer distributions in the triangular channel with ejection holes.