Effect of Ground Obstacle of Different Aspect Ratio on Wake Vortex Dissipation (Invited)

The employment of obstacles to accelerate dissipation of aircraft wake vortex near ground was proposed by DLR, with several subsequent studies on the effect of the obstacles under different atmospheric conditions. In collaboration with DLR, the NTU research team employed large eddy simulation to study the effect of obstacle shape on the dissipation rate and propagation speed of vortex breakup. Simulation results have shown that while the shape of the obstacle influences the propagation speed of vortex breakup, the flow-facing area of the obstacles is the major contributing factor deciding the magnitude of circulation reduction on top of the obstacle. The current study aims to investigate the effect of the aspect ratio of obstacle on vortex dissipation while holding the biggest contributor to reduction of circulation, form drag from the obstacle projected area, constant. Our simulation data has shown that, with every other parameter remained constant, the aspect ratio of obstacle makes negligible difference to the dissipation rate of wake vortex. The result suggested that the height of the obstacle could be further reduced into a less intrusive profi le and lessen the impact of these obstacles on airport operations.

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