Flight-Simulator Study of Airplane Encounters with Perturbed Trailing Vortices

摘要

This study provides a preliminary, but concrete, assessment of the potential benefits of causing the breakup of airplane trailing vortices via large-scale instability, resulting in vortex rings. The 737-300 flight simulator is used to model the autopiloted response of an airplane encountering the vortices at different stages in the breakup process. A series of encounters with straight vortices is used to establish a baseline response. For the early stages of the vortex breakup, the vortices are modeled as wavy vortex filaments. For the late stages of the vortex breakup, the vortices are modeled as vortex rings, whose shape is based on experimental observation. The primary results of the study are presented in a collection of contour plots for the maximum bank angle that occurs during an encounter. The bank angles are given as a function of the horizontal and vertical vortex-intercept angles. The results show a significant reduction in the maximum bank angle, experienced by the encountering airplane, as a result of the vortex breakup. The simulations show a continuous reduction in the level of upset as the vortices become increasingly wavy and ultimately break up into rings. The most significant reductions (both in terms of the magnitudes of the upset and the likelihood of their occurrence) result from the formation of vortex rings. The results suggest that the controlled breakup of the vortices could be exploited to enable reduced airplane separations, based on a vortex-destruction concept in addition to vortex avoidance.