Wake vortex transport in proximity to the ground

Abstract

A sensitivity study for aircraft wake vortex transport has been conducted using a validated large eddy simulation (LES) model. The study assumes neutrally stratified and nonturbulent environments and includes the consequences of the ground. The numerical results show that the nondimensional lateral transport is primarily influenced by the magnitude of the ambient crosswind and is insensitive to aircraft type.In most of the simulations. the ground effect extends the lateral position of the downwind vortex about one initial vortex spacing (h,,) in the downstream direction. Further extension by as much as one h,, occurs when the downwind vortex remains "in ground effect" (ICE) for relatively long periods of time. Results also show that a layer-averaged ambient wind velocity can be used to bound the time for lateral transport of wake vortices to insure safe operations on a parallel runway.

Wind Impact on Single Vortices and Counterrotating Vortex Pairs in Ground Proximity

“…The first flight experiments [17] and laboratory observations [18,19] date about 50 years later. These early works were followed by numerical simulations [12,14,[20][21][22][23][24][25][26][27][28][29][30][31], laboratory experiments [22,32], and field experiments [3,4,[33][34][35][36]. A survey on vortex interactions with walls is given in [11].…”

Ultrasonic Method for Aircraft Wake Vortex Detection

“…A numerical simulation by Corjon and Poinsot [5] finds that ground proximity and resulting viscous flow produce a secondary pair of vortices that induce the original wake vortices to move upward; experimental studies confirm formation of secondary vortices as a result of proximity to the ground [6]. Proximity to the ground has also been shown in observed data and numerical simulations to produce lateral separation of the vortex pair [5,7].…”

“…Behavior of wake vortices is widely shown to be altered by proximity to the ground [5][6][7], as well as by various atmospheric conditions [8,9]. A numerical simulation by Corjon and Poinsot [5] finds that ground proximity and resulting viscous flow produce a secondary pair of vortices that induce the original wake vortices to move upward; experimental studies confirm formation of secondary vortices as a result of proximity to the ground [6].…”

“…Previous research shows wake vortex dissipation can be enhanced by a variety of factors [5][6][7][8][9] and circulation may reduce to harmless levels well before the mandatory separation distance has been reached. Vortices can also be advected out of the flight path by local winds, leaving a safe runway available for air traffic.…”

Wake Turbulence Limits on Paired Approaches to Parallel Runways

“…NASA's aircraft vortex spacing system (AVOSS) 6 program has investigated both of these issues, particularly as related to single-runway operations. In addition,Hamilton and Proctor 7 have conducteda thoroughanalysis of how the crosswind affects lateral wake transport using a largeeddy simulation (LES) model. The AVOSS method of handling wind measurement accuracy is used in this paper.…”