Control of multiple vortices over a double delta wing

Active and passive control of leading-edge vortices over a 70°/50° double delta wing by means of jet blowing and bleed were studied experimentally in a closed-loop water tunnel using particle image velocimetry (PIV) measurements. Depending on the jet location and yaw angle, the strake vortices and the wing vortices could be separated further away from each other thus resulting in weak interactions or the interactions between the strake and wing vortices could be intensified thus leading to an earlier merge. Ingestion of jet turbulence into the vortices appears to promote merging. Evidence suggests that significant forces/moments could be produced even at low momentum coefficients. Passive bleed with estimated momentum coefficients of the order of 0.1% can also promote vortex merging. Secondary vortex can be strengthened and alter the vortical flow structure over the delta wing. It was found that bleed is more effective at lower wing incidences.