Simulation Methods for Aircraft Encounters with Deformed Wake Vortices

Abstract

Simulation of aircraft wake-vortex encounters is regularly applied in the research toward revised aircraft separation minima. Most encounter flight simulation studies have used a pair of straight counter-rotating vortices. However, after being shed by the generating aircraft, the wake vortices begin to develop a growing deformation due to the long-wave Crow instability, especially under low-turbulent atmospheric conditions when vortices decay slowly. In this study, two methods for simulation of aircraft encounters with such perturbed wake vortices are described and compared. The first method uses a vortex simulation model, which is based on analytical models of the deformation that consider the large-scale vortex shapes. The second method applies vortex-velocity fields from high-fidelity largeeddy simulations. It offers the highest possible level of realism and is used as the reference. The resulting aircraft responses induced by wavy vortices and vortex rings are reproduced with good quality by the vortex simulation model. The comparison of both methods shows that the vortex simulation model captures the overall impact of vortex deformation on the aircraft upsets. It can be used for future safety assessments that require a large number of encounter simulations.

A Deep Learning Framework Based on Multisensor Fusion Information to Identify the Airplane Wake Vortex

“…As an important basis for studying the dissipation structure and characteristics of airplane wake, the field wind field measurement for wake can accumulate a large amount of measured data, which can be used to better mine the temporal and spatial characteristics of wake in different wind fields and through the auxiliary monitoring of the airport surveillance radar, so as to make the identification results more accurate, which is of great practical significance [5,6,[31][32][33][34][35][36].…”

A review of recent wake vortex research for increasing airport capacity

“…Simulations have been used to examine the influence of vortex curvature on encounter severity ( [80], [81], [82], [83], [84]). As noted by Crow [11], wakes deform as a result of the long-wave Crow instability, which in turn is driven by the ambient turbulence and in later stages by the temperature stratification [83].…”

“…Simulations have been used to examine the influence of vortex curvature on encounter severity ( [80], [81], [82], [83], [84]). As noted by Crow [11], wakes deform as a result of the long-wave Crow instability, which in turn is driven by the ambient turbulence and in later stages by the temperature stratification [83]. With increasing turbulence intensity and increasing turbulence integral length scales the vortex topology is becoming more complex and the classical shape of the Crow instability and the ring formation is getting lost in favor of superimposed random deformations caused by large scale turbulent eddies [34].…”

Simplified vortex methods to model wake vortex roll-up in real-time simulations for fuel-saving formation flight

“…For the investigation of vortex effects on a trailing aircraft, very high accurate methods, like Large Eddy Simulations (LES), have been applied, e.g. by Bieniek et al [14]. There, the vortex flow field was pre-computed for a certain distance behind the generating aircraft and stored in a "box", from which the wind field can be used.…”