A Numerical Study of the Scaling and Control of Crossing Shock-Wave/Turbulent Boundary-Layer Interactions

To improve the design process of hypersonic vehicles, the performance of high-speed inlets must be evaluated through their entire flight domain. Hypersonic inlets are optimized for cruise conditions, but off-design operation introduces significant sources of uncertainty. Although many studies of high-speed inlets exist, much work is still needed in understanding the uncertainty associated with extrapolating ground test data to true flight conditions. Many ground facilities can match flight Mach numbers; however, many of these facilities are limited in Reynolds number ranges and matching true flight temperatures is difficult without vitiating the air.

To assist in understanding the uncertainty associated with these experimental complications, the present study conducted a numerical campaign observing the effects of scaling Reynolds number, stagnation temperature, and gas and wall thermal models on high-speed, crossing-shock-wave/boundary-layer interactions. The interaction was generated by two symmetric, sharp fins, and this geometry is intended to be representative of high-speed inlets. The primary flow feature observed was the distortion levels downstream of the interaction. Distortion is difficult to measure experimentally and is a commonly observed metric determining the performance of an inlet. It was found that distortion decreased with an increase in Reynolds number and compressible shape factor of the incoming flow.

The performance of vortex generators in passively controlling this interaction was also studied. These devices were shown to delay separation, however they also increased distortion levels at the outlet, and induced momentum losses compared to the baseline case without flow control.