De-Stabilization of Aircraft Wake Vortices

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ABSTRACT Proposal Number: CTS-9632579 Principal Investigator: Marcus The goal of this work is the destabilization of trailing tip vortices from commercial aircraft. This is a persistent problem that was identified more than thirty years ago. The strength of these vortices is so large that even another commercial jet can be upset if encountering a vortex structure at too close a range. A rash of crashes in the 60's and 70's required the FAA to set stringent spacing standards for landing aircraft that has had a severe impact on the capacity of our airports. Over the years there has been an intense effort directed at finding methods for breaking up these very coherent vortex structures, mainly through modifications to to the wing and its control surfaces. None of this work has lead to anything of practical use. In this study, wake vortices are weakly modified by injecting small amount of fluid at the wing tips in a precisely controlled manner. A novel semi-analytical method utilizing degenerate perturbation theory will be used to explore a broad range of combinations of angle, location, spatial structure and temporal rate of the injected fluid that leads to fast-growing short wave length instabilities. One effect of the fast-growing short wave length instabilities is to increase the core size quickly, which reduces the intensity of the swirl velocity. A secondary, and perhaps more important effect of increase core size is enhanced role that the Crow instability mechanism can play in the final decay of the trailing vortex system.