Large Eddy Simulation of Supersonic Impinging Jets

Large eddy simulations are achieved for a stable and an unstable flow regime of a supersonic jet impinging on a flat plate corresponding to a nozzle-pressure ratio of 4 and two nozzle-to-plate spacings equal to 4.16 and 2.08, respectively. The unsteady case is analyzed to assess the relationship between flow unsteadiness and the production of acoustic tones. Average flow structures and velocity profiles given by LES match the experimental results. Phase-locked diagnostics also agree with experimental observations. Wave analysis of an instability loop on a specific path gives quantitative evaluations of the perturbation propagation during the cycle. A feedback formula for predicting the frequencies of discrete tones is applied with success to the present case, assuming a convective downstream propagation following the inner mixing layer.