Experimental Studies of Tab Geometry Effects on Mixing Enhancement of an Axisymmetric Jet.

The velocity field associated with a nozzle flow emanating into a co-flowing stream was measured using a Laser Doppler Velocimetry(LDV) technique. The present work concentrates on the effect of small tabs introduced at the nozzle exit plane on mixing of the jet. The effect of tab geometry on mixing rate has been studied. The principal objective of the present measurements was to study the effect of introducing a 3-D shape to the tab geometry, rather than plain 2-D tabs of small thickness. Three different 3-D shape tabs were studied. The mixing improvement for all 3-D shape tabs was found to be substantially reduced compared to the plain 2-D tab results for the same projected area. Therefore, attempts to reduce the drag and performance loss penalty of the tabs were accompanied by significant reductions in tab mixing effectiveness.