Abstract
This paper presents an experimental and numerical study on loss mechanisms of two high-turning compressor cascades at supercritical flow conditions. It is part of a comprehensive advanced compressor blade development program, in which three cascades were designed at a higher supercritical speed (M 1 = 0.87) for a transonic fan stator hub section. The cascades had the same solidity and blade chord but differed significantly in blade profiles. The baseline profile was a conventional controlled diffusion airfoil. The other two were state-of-the-art optimized designs and were experimentally confirmed to outperform the baseline. The first optimized cascade (optimized A) and its performance was published in Song and Ng (Song, B., and Ng, W., Performance and Flow Characteristics of an Optimized Supercritical Compressor Stator Cascade, Journal of Turbomachinery, Vol. 128, July 2006, pp. 435-443). The current paper focuses on comparing the baseline and the second optimized cascade (optimized B) to complement the first publication. Cascade test results are presented to show significant loss reduction (about 30%) from the baseline to the optimized profiles. Experimental and numerical analyses to understand the flow physics underlying the loss reduction are detailed using the following: wake profile, blade surface Mach number, shadowgraph, and blade surface flow visualization. It was found that severe boundary-layer separation occurred in the baseline cascade, whereas the boundary layer of the optimized cascades was well controlled from separation. An understanding of the low-loss flow pattern and design philosophy for high-turning compressor blades at higher supercritical flow conditions, exemplified by the two optimized cascades and relative to the controlled diffusion airfoil, is summarized.
Published Version
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