Vortex shedding mechanism from a triangular prism in a subsonic flow

Publisher Website
Google Scholar
Abstract
Alternate periodic vortices shed from a triangular prism arranged as either a wedge or a reversed wedge are studied experimentally at a Mach number of 0.377 and at a Reynolds number of 1.73 × 105 (based on the prism height). It is found that the flow around the triangular prism arranged as a wedge (referred to as prism 1) separates at the sharp trailing edges, and the main vortices are generated immediately after the separation. No secondary vortex is generated around prism 1 ; however the flow around the other triangular prism arranged as a reversed wedge (prism 2) separates at the sharp leading edges. The main vortices are not formed immediately after the separation; rather their formation is finished either over or under the trailing edge. In this case, strong secondary vortices on and beneath the trailing edge are generated by the upper and lower main vortices, respectively. The vortices behind prism 1 are weaker than those behind prism 2, but the rate of the vortex shedding process behind prism 1 is higher than that behind prism 2. That is, the weaker the vortices are, the higher the rate of the vortex shedding process (or the Strouhal number) is, and vice versa. The vertical spacing between the loci of the upper and lower main vortices behind prism 1 is wider than that behind prism 2, but the width of the wake behind prism 1 is narrower than that behind prism 2. It is suggested that the Strouhal number for a wedge is sensitive to the front shape (i.e. the wedge angle), but that for a reversed wedge is not sensitive to the rear shape. Finally, the vortex shedding mechanism from a triangular prism arranged as either a wedge or reversed wedge has been proposed. It is concluded that, irrespective of the arrangement, vortex shedding is maintained by the unstable system of three vortices generated in the vortex formation region, but the effect of the downstream oscillating wake on vortex shedding is not critical.

This publication has 14 references indexed in Scilit: