PIV investigation of the 3D instantaneous flow organization behind a micro-ramp in a supersonic boundary layer

The flow field resulting from a single micro-ramp in a Ma=2.0 supersonic boundary layer is investigated using tomographic particle image velocimetry (Tomo-PIV). The measurements were carried out within two volumes behind the micro-ramp. Mean flow characteristics are analyzed, evidence of the streamwise vortex pair is given. In the instantaneous flow, a Kelvin-Helmholtz (K-H) instability developing in the wake of the element is revealed, and the K-H vortices are further identified. A conceptual model is provided to describe the instantaneous flow organization generated by a single micro-ramp