Control of Shock-Induced Flow Separation Using Rectangular Air-Jet Vortex Generators

In the context of controlling shock-induced separation on aerospace vehicles, the separation control effectiveness of steady air-jet vortex generators (AJVGs) with rectangular jet orifices of [Formula: see text] is experimentally investigated and compared against existing results of elliptical ([Formula: see text]) and circular ([Formula: see text]) AJVGs under otherwise identical conditions. All the jets are spanwise-inclined and are characterized by the same hydraulic diameter. A 24° compression-ramp interaction at Mach 2.52 serves as the baseline case. Oil-flow visualizations revealed an improved effectiveness for the rectangular AJVGs compared to the circular AJVGs but comparable to that of the elliptical AJVGs. Furthermore, the rectangular AJVGs induce a stronger spanwise skew in the direction of jet injection. Particle image velocimetry measurements revealed that rectangular AJVGs are similar to the elliptical AJVGs in generating a stronger streamwise vorticity than circular devices. However, unlike the elliptical case, they experience stronger jet–jet interactions, likely due to the formation of additional small-scale structures from the sharp corners in the jet orifices. Snapshot-proper orthogonal decomposition of the velocity fields revealed the formation of high-energy wall-normal coherent structures by the rectangular AJVGs. Nevertheless, there is minimal modification to the overall structure of the shock-wave/turbulent-boundary-layer interactions (SWBLIs) due to AJVGs, indicating that the SWBLIs are generally a robust phenomenon.