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Experimental Investigation of Convective Heat Transfer and Pressure Losses in Turbine Blade Internal Cooling Channels
Abstract
Serpentine, multi-pass cooling passages are used for cooling advanced gas turbine blades. In open literature, most internal cooling studies use a fixed cross-sectional area for multi-pass channels. Studies that use varying aspect ratio channels, along with a guide vane to direct the turning flow, are scarce. This study investigates the effect of using different guide vane designs on both detailed heat transfer distributions and pressure loss in a multi-pass channel with an aspect ratio of (4:1) in the entry passage and (2:1) in the second passage downstream of the vane(s). The first vane configuration is one solid-vane with a semi-circular cross-section connecting the two flow passages. The second configuration has three broken-vanes with a quarter-circular cross-section; two broken vanes are located downstream in the first passage, and one broken vane is upstream in the second passage. Detailed heat transfer distributions were obtained on all surfaces within the flow passages using a transient liquid crystal method. Results show the quarter-circular vane design provides higher overall averaged heat transfer enhancement than the semi-circular vane design by approximately 9% with penalty of higher pressure drop by 6%, which yields higher thermal performance by 7%, over a Reynolds number range from 15,000 to 45,000.
The second part of this study is an experimental investigation of heat transfer and friction for fully developed turbulent air flow in a rectangular channel (AR=3). 90-deg., 45-deg. (parallel and cross), and V-shaped ribs with (e/Dh) = 4.1% and (P/e)=10 are placed on one, two, or four-sides of the channel to investigate the effects of number of ribbed walls on the thermal performance of the channel for a Reynolds number range (Re=5,000−60,000). Heat transfer coefficients and friction factors are enhanced with the increase of number of ribbed walls. Using these experimentally measured friction and heat transfer data, along with law of wall similarity, more robust correlations are obtained. Heat transfer designers can use these correlations with the similarity laws to predict friction and heat transfer in cooling channels with different number of rib-roughened walls for different rib configurations over a roughness Reynolds number range.
Citation
Alsaleem, Sulaiman Mohammed S (2022). Experimental Investigation of Convective Heat Transfer and Pressure Losses in Turbine Blade Internal Cooling Channels. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /197842.