A Study of Supersonic Compression-Corner Interactions using Hybrid LES/RANS Models

This research has developed a new hybrid large-eddy /Reynolds-averaged Navier-Stokes turbulence closure strategy specifically designed for strongly interacting, wall-bounded flows. The model differs from its predecessor in that the need to pre-calibrate a model constant is removed through the use of ensemble-averaged turbulence information to estimate an outer-layer turbulence length scale. The model has been applied to a variety of shock / boundary layer interactions and has shown a good level of predictive capability for both mean and second-moment quantities. A specific result of the shock / boundary layer interaction study is a strong correlation between the most probable time of a fluid within the recirculation region formed through shock interaction and the dominant low-frequency signal of the interaction. This provides evidence that the appearance of a low-frequency mode of separation-shock unsteadiness is intimately connected with the structure of the backflow region and the mean entrainment patterns. With this knowledge in place, it may be possible to predict low-frequency dynamics of complicated interactions by examination of the mean structure of the interactions. The LES/RANS model was also tested for turbulent flow over an airfoil near static stall as an initial step toward its use in predicting dynamic stall The original document contains color images.