Supersonic Flow over a Ramped-Wall Cavity Flame Holder with an Upstream Strut

Nonreacting supersonic airflow over a wall cavity with a rear ramp both with and without an upstream strut is studied with hydroxyl-tagging velocimetry and large-eddy simulation (LES). An OH grid formed by crossing 11 lines by 11 lines is used to obtain velocities at similar to 120 grid points. The OH grid is tracked with a new template-matching method that determines both linear and rotational displacements. Mean and rms fluctuation velocity profiles both with and without the strut are analyzed and compared with results obtained from LES, and there is good overall agreement between the two methods. The experimental and LES results demonstrate that installing an upstream strut increased cavity recirculation along the centerline relative to the no-strut configuration. In addition, the shear layer is observed to grow more quickly and impinge higher on the ramp wall. Some disagreements are found in the measured and predicted propagation of the weak compression wake formed by the trailing edge of the strut and in the location of the velocity gradients in the cavity shear layer; possible reasons are identified and discussed for future study.