EPTT 2020

12th Spring School on Transition and Turbulence

AIRCRAFT WING TIP VORTICES DYNAMICS WITH CROSS WIND EFFECT USING THE LARGE EDDY SIMULATION (LES) THEORY

Submission Author: Marcos André de Oliveira , MG
Co-Authors: Marcos André de Oliveira, Paulo Guimarães de Moraes, Luiz Antonio Alcântara Pereira
Presenter: Marcos André de Oliveira

doi://10.26678/ABCM.EPTT2020.EPT20-0070

 

Abstract

An aircraft during landing or takeoff operations at airports around the world detaches large vortical structures, which can interfere with other aircraft. In general, the aircraft wing tip vortices persist for significant distances, present a circulation proportional to aircraft size and aircraft velocity (Zheng and Ash, 1996), interact intensely with the ground plane (Hirata et al., 2002), and still are influenced by effects of cross wind conditions. For interests of safety, conservative separation distances between two aircrafts are adopted attempting to avoid such interference (Wakim et al., 2017). However, for the operational optimization of the airports, it is necessary to reduce the interval between two consecutive landing or takeoff operations (Wakim et al., 2017; Hirata et al., 2002). In past work by Ricci et al. (2003), a pair of counter vortical structures, formed by elemental Lamb vortices, was utilized to effectively consider the deformation of such structures during their impact with the ground. They blended the Lagrangian vortex method with LES modeling (Alcântara Pereira, 2002), the latter to take into account the sub grid-scale phenomena. They also used the images method to automatically satisfy the impermeability boundary condition. The elemental Lamb vortices were only used for the desingularization of the velocity filtered field computation (Mustto et al., 1998). The simulations were performed at Reynolds number of Re=7,650 and the primary vortical structures trajectories were successfully compared with experimental results. However, they do not consider effects of cross wind conditions and parallel computing. The final processing time of a typical simulation is expensive because of the Biot-Savart law. In this work, the two-dimensional Lagrangian vortex method with LES modeling presented by Ricci et al. (2003) is improved aiming to reduce the final processing time of the simulations. The aim here is triple: (i) Elemental Lamb vortices are used in all computations dispensing the potential model; (ii) The local eddy viscosity computation, necessary to each Lamb vortex during each time step, is accelerated through a structure of the boxes developed by Andrade et al. (2016); (iii) Through parallel computing (OpenMP) in Fortran, are computationally integrated the expensive approaches of the Lagrangian vortex method and image method for accuracy and precision of the results, including cross wind conditions. Lastly, quantitative and qualitative results are presented at different Reynolds numbers, namely, 7,650; 10,000; 100,000 and 1,000,000, in dimensionless cross wind conditions, namely, 0, 0.02 and 0.04. The chosen example was of a Boeing 757-200, which is representative in aviation problems.

Keywords

Large Eddy Simulation (LES), Lagrangian methods, OpenMP-Fortran, Image method, Aircraft Vortex Wake

 

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