Experimental Investigation on the Effect of Ring Tab on Mixing Enhancement of Subsonic Jets

For thrust vectoring, combustion characteristics, infrared radiation reduction, and aeroacoustics noise mitigation, the mixing enhancement and core length reduction of a jet must occur without a substantial loss of thrust. Manipulating flow parameters enables the enhancement of the jet mixing process. Nozzle exits fitted with varying tab designs have the potential to alter the flow characteristics in the subsonic jets. The present study uses a ring tab to investigate the influence of the jet spread. These tab configurations are the source of creating counter-rotating vortices of varied sizes due to their even curvature in the plane of the flow. Non-uniform vortices at the orifice perimeter cause differential jet spread, resulting in axis switching and improved mass entrainment properties. The experimental results of the ring tab are compared with the free jet configuration at subsonic exit Mach numbers 0.4, 0.6 and 0.8. The Ring tab showed a significant decrease in the potential core, with reductions of 40%, 60% and 91.67% at Mach numbers 0.4, 0.6 and 0.8, respectively, indicating a substantial improvement in jet mixing. Additionally, the jet decay was faster than the free jet, demonstrating the potential of the ring tab in altering flow characteristics. The radial profiles and Mach contour plots illustrate the Mach decay, indicating the rate at which the jet spreads and the jet deflection from its centerline. This study presents a new tab configuration by providing a single circular ring tab instead of the typical dual tab layout. The main objective of this experimental study involving ring tab is to enhance jet mixing and perhaps decrease the core length, with potential applications in reducing noise and providing thrust vectoring in aircraft engine jets.