Experimental and Numerical Study of Flow Topology Past Micro-Vortex Generators

Abstract

Detailed experimental and numerical visualizations of the flow past a micro vortex generator (MVG) in the form of a ramp with swept sides in a Mach 2.5 flow revealed a complex near-field topology. The incoming flow separated over the leading edge of the MVG despite the ramp angle being below the threshold for incipient separation. The separation over the MVG protuberance produced a weak trailing horseshoe vortex system. The attachment line shows a saddle/foci combination on each side of a nodal point of attachment. The flow over the top of the MVG separated off the slant edges to produce a large primary vortex pair. This large primary vortex pair induced two secondary vortex filament pairs, one off the top of the MVG and another at the corner of the MVG with the flat plate. Extra complexities were revealed at the trailing edge with at least two pairs of saddle/foci combinations observed. It is postulated that vortex filaments spring from the various saddle/foci combinations as these were not observed experimentally or computationally. Symmetry breaking due to flow unsteadiness was also observed in the MVG wake.