Experimental Investigation of Two-Stream Mixing Flow with Multiple Tabs

Vortex-generating tabs arranged in the form of an array have been examined experimentally using a laser Doppler anemometer in a two-stream mixing flow situation. The vortex-generating tabs are the 'delta tabs,' i.e., triangular-shaped protrusions into the flow attached to the trailing edge of the splitter plate. A velocity ratio of 2:1 (upper and lower) between the two coflowing streams was used. Three arrangements for the tabs are investigated. Case 1 has all of the tabs located on the high-speed side. The tabs are located alternatively on either side of the splitter plate for case 2, and finally, case 3 is similar to case 2, but the tab on the low-speed side is tilted upstream (i.e., similar to a delta-wing vortex generator). Mutual cancellation between streamwise vortices rotating in the opposite sense was observed in case 1, whereas in case 2 the merging of streamwise vortices rotating in the same sense had delayed the decay of the streamwise vorticity. For case 3 the upstream tilted tab appeared to have generated relatively weak streamwise vortices so that they were canceled off by the vortices generated on the high-speed side near the trailing edge. Finally, the turbulence characteristics for each case are presented and discussed.