Experimental Investigation of Conical Tabs for Mixing Enhancement in Subsonic Circular Jets

Dual conical tabs for passive mixing enhancement in subsonic circular jets are investigated experimentally. A convergent nozzle with and without diametrically opposed half-cone tabs is tested at the exit Mach numbers 0.2, 0.4, 0.6, and 0.8, and jet development is characterized using centerline and radial Pitot pressure measurements. The conical tabs generate counter-rotating streamwise vortices that increase entrainment and accelerate jet core decay relative to the baseline circular jet. The tabbed configuration reduces the potential core length by up to approximately 50–81% over the tested Mach number range and produces larger geometric mean half-widths downstream, indicating substantially enhanced jet spreading. Therefore, these passive modifications provide a simple and robust means for intensifying jet mixing, with potential relevance to combustion optimization, and reduction in the jet signatures in propulsion applications.