Numerical investigation of mixing performance for controlled supersonic jet

In the present study, the mixing characteristics of the Mach 1.86 jet from a convergent-divergent nozzle of square cross-section from inlet to exit were investigated numerically. The jet studied were uncontrolled and controlled with limiting tab of rectangular and circular cross-sections. The nozzle pressure ratio is varied from 4 to 6 with a step size of one, leading to the confinement of the present study for the over-expansion and near correct expansion levels of the jet. It is observed that the core length, which is a direct indication of the extent of jet mixing, reduced significantly for the jet controlled with limiting tab as compared to that with the uncontrolled counterpart. Also, among the circular and rectangular limiting tabs, the tab with rectangular cross-section caused maximum core length reduction. The jet spread and the waves prevailing in the jet field were studied and visualized using pressure profiles and Mach contours, respectively. The present work may be used in understanding and solving complex phenomena occurring in the fields of aeroacoustics noise suppression, reduction of base heating of launch vehicles, supersonic combustion, mitigation of infrared radiations due to chimney smoke, etc., where jet mixing is highly desirable.