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Open AccessArticle

Effect of Incidence Angle on Entropy Generation in the Boundary Layers on the Blade Suction Surface in a Compressor Cascade

by Lei Shi and Hongwei Ma *
School of Energy and Power Engineering, Beihang University, Beijing 100191, China
*
Author to whom correspondence should be addressed.
Entropy 2019, 21(11), 1049; https://doi.org/10.3390/e21111049
Received: 28 September 2019 / Revised: 19 October 2019 / Accepted: 25 October 2019 / Published: 27 October 2019
(This article belongs to the Special Issue Entropy Production in Turbulent Flow II)
The entropy generation that occurs within boundary layers over a C4 blade at a Reynolds number of 24,000 and incidence angles (i) of 0°, 2.5°, 5°, 7.5°, and 10° are investigated experimentally using a particle image velocimetry (PIV) technique. To clarify the entropy generation process, the distribution of the entropy generation rates (EGR) and the unsteady flow structures within the PIV snapshots are analyzed. The results identify that for a higher incidence angle, the separation and transition occur further upstream, and the entropy generation in the boundary layer increases. When the separation takes place at the aft portion of the blade, the integral EGR decrease near the leading edge, remain minimal values in the middle portion of the blade, and increase sharply in the vicinity of the mean transition. More than 35% of the entropy generation is generated at the region downstream of the mean transition. When the separation occurs at the fore portion of the blade, the contributions of mean-flow viscous dissipation decrease to less than 20%. The entropy generation with elevated value can be detected over the entire blade. The entire integral entropy generation in the boundary layer increases sharply when the laminar separation bubble moves upstream to the leading edge. View Full-Text
Keywords: entropy generation; transitional boundary layer; turbulence; incidence angle; particle image velocimetry; compressor cascade entropy generation; transitional boundary layer; turbulence; incidence angle; particle image velocimetry; compressor cascade
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Shi, L.; Ma, H. Effect of Incidence Angle on Entropy Generation in the Boundary Layers on the Blade Suction Surface in a Compressor Cascade. Entropy 2019, 21, 1049.

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