The interaction of three-dimensional vortex flows

Abstract

The interaction of three dimensional vortex ows was investigated through vortex shedding o a discontinuous edge. Two 90 edges (up and downstream edges) were separated by an o set. The size of the o set (5mm, 10mm and 20mm) and the Mach number (Mach 1.32, 1.42 and 1.6) were the key parameters investigated. Experi- mental images were taken and computational simulations were run; a close relation was found between the two. This enabled the three dimensional e ects of the ow to be studied and analysed. It was found, as the o set increased in size; the vortices shed o the up and downstream edges took a longer time to merge and the strength of the interaction was weaker. The vortex topology changed with a larger o set; the downstream vortex was thinner (in terms of cross sectional diameter), which is an indication of a change in denisty, than the rest of the vortex along the downstream di raction edge, adjacent to the o set. This particular feature was more prevalent at lower Mach numbers. The e ects of a higher Mach number were to increase the rate of dissipation of the vortices, lengthen the shear layer and make the vortex pro le elliptical.