Combustion-related shear-flow dynamics in elliptic supersonic jets

Abstract : An elliptic jet having an aspect ratio of 3:1 was studied and compared to a circular jet at three Mach numbers: M = 0.15, 1 and 1.3. Hot-wire measurements and Schlieren photography were employed in this study. The superior mixing characteristics of an elliptic jet relative to a circular jet, which were found in previous works in subsonic jets, prevail in the sonic jet and are further augmented by the shock structures of the supersonic underexpanded jet. The major and minor axes switch at a distance of 3 diameters from the nozzle, and the spreading rate of the minor axis side is twice that of a subsonic jet. The experimental data are supported by results of the linear instability analysis of the supersonic elliptic jet which show that the initial vortices are bending at the major axis side in a similar way to the process which occurs in a subsonic elliptic jet.