A joint experimental-numerical study of turbulent structures in supersonic spatially-developing turbulent boundary layers*

The evolution of spatially-developing turbulent boundary layers (SDTBL) is studied experimentally and numerically at a Mach number of 1.25. Experiments are performed on SDTBL over a zero-pressure gradient isothermal flat plate, generated by means of a shock tube. The primary experimental observation includes flow visualization using a high speed shadowgraph system at 30,000 frame per second (fps). The shadowgraph image sequences allow us to track and assess the different turbulent structures and events inside the boundary layer by detecting density changes across the field of view.  Direct Numerical Simulation (DNS) of compressible SDTBL is also carried out at similar experimental conditions. The obtained high spatial/temporal resolution numerical information is employed for evaluating the wall-normal thermal transport phenomena and the Strong Reynolds Analogy (SRA). Focus is given to the assessment of flow compressibility on the dynamics of turbulent coherent structures. This presentation will emphasize the calibration effort of the numerical model in order to capture the observed flow structure.