Wake Vortex Model for Real-Time Flight Simulation Based on Large Eddy Simulation

Spence, Graham; Moigne, Alan Le; Allerton, D. J.; Qin, Ning

doi:10.2514/1.23761

Cited by 17 publications

(10 citation statements)

References 31 publications

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“…With the current and growing need for new technologies to lower fuel costs, and for new air traffic control (ATC) procedures to increase the capacity of an already busy airspace without compromising safety (11) , realistic models of aerodynamic coupling between air-vehicles in close proximity need to be developed and the risks and issues associated with wake vortex evolution and encounter need to be assessed. Previous techniques (12) used to model vortex-induced effects can be divided in two main categories: (i) theoretical and experimental methods using look-up databases (from CFD models (13,14) , wind tunnel and/or flight test measurements (15) ); (ii) computational methods (16) . The latter include, from the simplest to the most involved: Prandtl's lifting line theory (single horseshoe vortex) (17)(18)(19)(20)(21)(22) ; Vortex Lattice Methods (VLM) with or without viscous core (23)(24)(25) ; improved methods taking account of the roll-up of the wake (7,(26)(27)(28)(29) .…”

Section: Introductionmentioning

confidence: 99%

Simulation of wake vortex effects for UAVs in close formation flight

2009

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y rel y-component of the relative distance between two UAVs in formation z rel z-component of the relative distance between two UAVs in formation disadvantage: not only are they extremely computationally demanding to handle in real-time, but these databases can only be used for a specified air vehicle and a range of flight conditions (32) . Simple computational methods are rapid, but the results are not always realistic or accurate enough. However, with increasing accuracy comes increasing computation time. Hence choosing a computational method to model the wake vortex involves finding a compromise between accuracy and rapidity of execution. This paper describes the development of a computational method and simulation models that incorporate wake vortex effects associated with air vehicles flying in close proximity. The aim has been to develop a generic wake vortex model which could be used for any type of wing geometry, and still produce results which could be used in a real-time synthetic environment. Using the same VLM to model both vehicles has allowed them to exchange position during simulations. The non-uniform vortex-induced wind and wind gradients acting on the trail aircraft have been approximated as effective wind and wind gradients and directly used within dynamic simulations, following the method developed by Dogan and colleagues (32)(33)(34)(35)(36)(37)(38)(39) .In the following sections, first the WVM, then the model integration process are described, followed by some results and conclusions, and an outlook on further developments. WAKE VORTEX MODELA one-lifting-line vortex lattice method for linear aerodynamic wing applications has been developed and implemented in MATLAB. The code (ELL) computes the steady-state velocity induced by the wake of one or more air-vehicles at a given location using Weissinger's extended lifting-line theory (40,41) , and supports 3D, subsonic multiwing designs with swept, tapered, twisted wings of any aspect ratio, with or without dihedral.Special care was used to maintain the symmetry between the leading and following air-vehicles in order to allow them to exchange positions during simulations. As a consequence, the modelling reference frame could not be attached to any particular air-vehicle. Hence, it was decided to work in the inertial NED (North East Down) frame: not only was this reference frame independent of UAV positions and orientations, but it presented advantages when interfacing the simulation with visualisation tools such as FlightGear (42,43) or AVDS (44,45) .

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Section: Introductionmentioning

confidence: 99%

Simulation of wake vortex effects for UAVs in close formation flight

2009

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“…Such an approach has been described by Spence et al 33 However, they used a complex data compression and management process in order to change the LES vortex velocity fields during a real-time simulation and adjust the vortex age dynamically to the current separation distance between generating and encountering aircraft. A much simpler integration method is used here.…”

Section: Wake Vortex Velocity Modelmentioning

confidence: 98%

Investigation of Encounters with Deformed Wake Vortices using a Monte-Carlo Simulation Methodology

Bieniek

Luckner

2014

6th AIAA Atmospheric and Space Environments Conference

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Flight simulation is an important tool for investigating the impact of a wake-vortex flow field on aircraft response and on the severity of wake vortex encounters as it allows to evaluate a huge variety of encounter parameters under controlled conditions without risk, at low costs and time-efficient. The majority of simulation studies has used a pair of counter-rotating straight vortices to represent the vortex wakes. However, as part of the decay process, the vortices develop a periodic long-wave deformation due to Crow instability that may lead to a breakup into vortex rings. The paper describes a methodology to perform Monte-Carlo simulations of aircraft encounters with such perturbed vortices. A high-fidelity six degree-of-freedom aircraft simulation is coupled with a wake encounter simulation that includes models of wavy vortices and vortex rings, that are fitted to wake shapes from pre-computed large-eddy simulations. Application of the methodology is demonstrated by assessing aircraft bank angle upsets from encounters with straight and deformed vortices for different test setups. First results indicate that the impact of wake deformation is strongly affected by the simulated encounter scenario. For a full-scale Monte-Carlo simulation with uniform parameter distributions and assuming the same and constant vortex strength, vortex rings exhibit a lower probability of experiencing bank angle upsets above a specific threshold, whereas only small differences between straight and wavy vortices are observed.

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“…For cases when the entire time-series cannot be preloaded into RAM, a time-step paging system has to be developed to avoid unacceptable losses of frame-rate if time-steps are loaded into RAM on demand. A multi-threaded paging system has been incorporated into the model developed at Sheffield (3) .…”

Section: Nomenclaturementioning

confidence: 99%

Wake vortex encounters in a flight simulator

Allerton¹,

Spence

2010

Aeronaut. j.

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A real-time model of a wake vortex has been developed for an engineering flight simulator, which enables studies to be undertaken into the effects of wake vortex encounters with civil transport aircraft. A brief summary of the methods used to create a vortex model and integrate it with a real-time flight simulator is presented. Tools have been developed to determine the structural loads on an aircraft during a simulated wake vortex encounter and to visualise the airframe loads. Four wake vortex encounters were flown with different pilot recovery strategies and automatic flight controls. It is clear from analysis of these results that it is difficult for a pilot to appreciate the margin of tail loading during an encounter and a prototype training display is outlined to enable pilots to fully understand the effects of rudder inputs in recovery from these events.

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Wake Vortex Model for Real-Time Flight Simulation Based on Large Eddy Simulation

Cited by 17 publications

References 31 publications

Simulation of wake vortex effects for UAVs in close formation flight

Simulation of wake vortex effects for UAVs in close formation flight

Investigation of Encounters with Deformed Wake Vortices using a Monte-Carlo Simulation Methodology

Wake vortex encounters in a flight simulator

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