Enhancement of wake vortex decay by air blowing from the ground

It is well-known that the long-lasted aircraft wake vortex above the airport runway jeopardizes flight safety. Therefore, the research on the enhancement of wake vortex decay is pretty much essential. The previous studies suggest that the wake decay process can be improved by introducing artificial perturbations [1]. For example, the plate lines on the ground can trigger the helical secondary vortex structures (SVS), propagating along with the primary vortices. As a result, the vortex decay will be enhanced. In the present research, active flow control methods on wake vortex decay, like air blowing or suction, are studied. Blowing/suction zones are embedded on the ground to generate airflow below the wake vortex tubes. Different sizes and shapes of the blowing/suction zones are tested. The large eddy simulation (LES) method is used to quantitatively investigate the blowing/suction effects on wake vortex decay. Furthermore, the coherent vortex structures observed and the acceleration mechanism on wake decay caused by active flow control are studied carefully. According to the present research, it is found that with a small blowing velocity (1.79 m/s) and a short blowing duration (13.15 s), the aircraft wake strength can be roughly reduced by 50% at t⁎=1. Based on the simulation results, it is revealed that the apparent effect on the wake vortex development is due to the detached vortex generated near the blowing zone rather than the blowing flow itself. Besides, a detached vortex with a scale of 0.2b0 is needed to achieve a better wake decay enhancement.