Maruyama D.,ONERA |
Maruyama D.,French Institute for Research in Computer Science and Automation |
Bailly D.,ONERA |
Bailly D.,Civil Aircraft Unit |
And 2 more authors.
AIAA Journal | Year: 2014
Many mesh deformation techniques developed in the past have been widely used, but for large deformations, the mesh properties can be severely altered. In particular, the mesh lines orthogonality near the boundaries can be lost. In this paper, a method initially proposed by Samareh ("Application of Quaternions for Mesh Deformation," NASA TM-2002-211646, April 2002) is developed to overcome this limitation and to provide a high-quality meshorthogonality preservation technique. Each node displacement is composed of a translation vector and a quaternion, which takes into account local mesh rotations. Algebraic unitary quaternion properties (Lie group algebra) are used to obtain a robust interpolation method. Two quaternion interpolation methods are compared, respectively: the spherical linear interpolation, and the Lie algebra linear interpolation. Furthermore, thanks to a new process (transformation division), the method becomes independent of the rotation center used. The accuracy and generality of the method is significantly improved by this new process, and different test cases (two-dimensional and threedimensional) are presented to illustrate the benefits obtained. Global mesh quality is shown to be preserved, especially local mesh orthogonality near the moving surfaces. The application to an iced airfoil shows the capability of the method to propagate very severe deformations while providing deformed mesh that enables accurate Reynoldsaveraged Navier-Stokes computational fluid dynamics calculations. Copyright © 2014 by ONERA. Source
Hue D.,ONERA |
Hue D.,Civil Aircraft Unit |
Vermeersch O.,ONERA |
Vermeersch O.,Transition and Acoustics Unit |
And 6 more authors.
AIAA Journal | Year: 2015
The friction component is responsible for more than 40% of typical civil aircraft drag. As a consequence, the issue of laminar flow has been of prime importance in aeronautics for many years now. This article is focused on Tollmien-Schlichting-induced transition and drag predictions of two-dimensional laminar airfoils obtained with experimental and numerical methods. In 2012, a test campaign in the ONERA-S2MA wind tunnel, including infrared acquisitions, pressure sensors, and wake analyses, allowed substantial data to be obtained on such airfoils in transonic conditions. To complete this study, two-dimensional fluid dynamics computations have been performed, either with a Reynolds-averaged Navier-Stokes solver using transition criteria or with a boundary-layer code combined with direct stability analysis. Furthermore, experimental (wake survey) and numerical (far-field theory) techniques allowing airfoil drag breakdown have been employed. Wind-tunnel and computational fluid dynamics transition predictions have been compared. Good agreement has been observed but the transition criteria may show some limitations in particular situations, such as long separation bubble development. The gains in lift and drag due to laminar flow have been quantified (natural vs triggered transition). Concerning drag reduction, the importance of the viscous pressure component has been highlighted. Finally, the effects of parameters such as angle of attack, Mach number, and Reynolds number on transition location and drag have been investigated. Copyright © 2015 by ONERA. Published by the American Institute of Aeronautics and Astronautics, Inc. Source