Dye visualization over double delta wing with various kink angles

In this study, the aim is to exhibit vortical behaviors of flow on double delta wings having 70° strake sweep angle and kink angles of 150°, 160° and 165° using dye visualization technique in a water channel. Experiments were performed at Reynolds numbers based on the chord length Re = 10,000 and 25,000 for angle of attack in the range 5° to 35°. The visualizations were performed for both end-view and cross-flow planes. The results revealed that the kink angle has a significant role on the interaction of vortices and the strake vortex breakdown locations. The interaction between the strake vortex and the wing vortex is dominant on the flow behaviors at α ≤ 10°. The flow behavior is affected by the kink angle. Two interaction mechanisms which are spiral and enveloping are observed. The spiral interaction alternates to enveloping interaction with increasing Reynolds number. Moreover, the trajectory of the strake vortex core moves outboard with increasing Reynolds number at α = 10°. For α ≥ 15°, Reynolds number is less effective on the strake vortex breakdown location and also the vortex breakdown locations move the apex gradually with increasing angle of attack. Wake-alike flow structure takes place after occurrence of the vortex breakdown since vortex core splits into disorganized small-scale vortices. On the other hand, development of the wing vortex is more complex than the strake vortex since it collapses near the vicinity of the junction.