Large-scale vortex generation (and bursting) using windshapers

Vortical structures have been a topic of interest in fluid dynamics for a long time and are present at every scale. With the recent growing interest in Advanced Air Mobility (AAM), the need to test these vehicles in such wind structures has grown as well. A large-scale vortex is being generated using multiple windshapers (multi-fan wind facilities) set at an angle with respect to each other. The high Reynolds number vortex is being investigated numerically and experimentally. The findings indicate that the vortex axial velocity exhibits a similar pattern as seen in the vortex breakdown phenomenon commonly appearing in swirling flows. The capability of modifying the inlet tangential and axial air-flow conditions in the experiments makes it possible to show that the occurrence of the vortex breakdown depends on the ratio between the rotational and the axial volume fluxes and occurs at a definite critical value. Furthermore, no hysteresis was found in contrast to low Reynolds numbers vortex breakdown.