LES loss prediction in an axial compressor cascade at off-design incidences with free stream disturbances

Leggett, J., Priebe, S., Shabbir, A., Sandberg, R.D., Richardson, E. and Michelassi, V. (2017) LES loss prediction in an axial compressor cascade at off-design incidences with free stream disturbances. ASME Turbo Expo (International Gas Turbines Institute), , Charlotte, United States. 26 - 30 Jun 2017. (doi:10.1115/GT201764292).

Abstract

It is well known that an axial compressor cascade will exhibit variation in loss coefficient, described as a loss bucket, when run over a sweep of incidences, and that higher levels of free stream turbulence are likely to suppress separation bubbles and cause earlier transition (see e.g. [23]). However, it remains difficult to achieve accurate quantitative prediction of these changes using numerical simulation, particularly at off-design conditions, without the added computational expense of using eddy-resolving techniques. The aim of the present study is to investigate profile losses in an axial compressor under such conditions using wall-resolved Large Eddy Simulation (LES) and RANS. The work extends on previous work by Leggett et al.[11] with the intention of furthering our understanding of loss prediction tools and improving our quantification of the physical processes involved in loss generation. The results show that while RANS predicts losses with good accuracy the breakdown of these losses are attributed to different processes, meaning that optimisation of a compressor cascade profile, based solely on RANS,
may be hard to achieve.

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Contributors

Author: E. Richardson

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