On the background of cooling jet flow on the optical window

the supersonic jet flow over a backward facing step was investigated via large-eddy simulation (LES). Based on the implicit sub-grid model

the numerical method utilized the seventh order WENO scheme for spatial discretion

which was validated by the simulation of the supersonic mixing layer. The computational model for supersonic jet mixing flow was identical to the wind tunnel experiment

and the Mach number of the free flow and jet flow were set as 3.4 and 2.5

respectively. The numerical simulation captured the complex flow structures of compressive and expansive waves

as well as the shearing mixing layer and boundary layers. The process of flow becoming unsteady and transiting to turbulence was predicted subtly. The position and shape of large-scale turbulent structures obtained from numerical simulation agreed with experimental images. By the analysis of instantaneous

averaged

and fluctuant flow field

the temporal and spatial evolution of flow structures were revealed

and the feature of density fluctuation was acquainted.