Numerical study of separated boundary layer transition under pressure gradient
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AbstractLarge-eddy simulation (LES) is conducted to study the transition process of a separated boundary layer on a flat plate with an elliptical leading edge. A streamwise pressure distribution is imposed and the free stream turbulence intensity is 3% to mimic the suction surface of a low-pressure turbine (LPT) blade. A dynamic sub-grid scale model is employed in the study and the current LES results compare well with available experimental data and previous LES results. The transition process has been analysed with a particular focus on primary instabilities at work. Streaky structures further upstream of the separation, known as the Klebanoff Streaks, have been observed. Typical two-dimensional Kelvin-Helmholtz (K-H) rolls are distorted in the separated region. When Klebanoff streaks passing over a full-span K-H roll, portion of the two-dimensional roll merges with the Klebanoff streaks and develop into chaotic three-dimensional structures, whereas the remaining undisrupted two-dimensional K-H rolls develop into Λ-vortex indicating that despite the disturbances before separation, the K-H instability may still be the main instability at work.
CitationLi. H., Yang, Z. 'Numerical study of separated boundary layer transition under pressure gradient', Proceeding of the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, 11-13 July 2016, Malaga, Spain.
JournalProceeding of the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, 11-13 July 2016, Malaga, Spain.
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