Evolution of Coherent Structures in Under-expanded Supersonic Impinging Jets

This study looks at the spatio-temporal dynamics of the coherent structures found in under-expanded supersonic impinging jets from a circular nozzle at a pressure ratio of 3.4 and standoff distances of 2d and 5d. In these jets the development of coherent structures within the shear layer and their interaction with a standoff-shock are the principle components of a fundamental non-linear acoustic feedback mechanism. Temporally resolved and phase averaged data for each case was generated from a three dimensional hybrid large-eddy simulation on a non-uniform structured cylindrical grid with computational domains consisting of approximately 30 million nodes. From these datasets we investigate the development of the energy, topology and turbulence interactions of the coherent structures as a function of their distance travelled along the shear-layer