Triangular tabs for supersonic jet mixing enhancement

Abstract

The mixing promoting capability of right-angle triangular tab with sharp and truncated vertex has been investigated by placing two identical tabs at the extremities of an exit diameter of a Mach 2 axi-symmetric nozzle. The mixing promoting efficiency of these tabs have been quantified in the presence of adverse and almost zero pressure gradients. It is found that, at all levels of expansion of the present study though the core length reduction caused by both the tabs are appreciable, the mixing caused by the truncated tab is superior. The mixing promoting efficiency of the truncated tab is found to increase with increase of nozzle pressure ratio (that is, decrease of adverse pressure gradient). For all the nozzle pressure ratios of the present study, the core length reduction caused by the truncated tab is more than 95%, with a maximum of 99%, at NPRs 7 and 8. The present results clearly show that the mixing promoting capability of the tab is the best when the jet is almost correctly expanded (that is with almost zero pressure gradient).