Application of a Navier-stokes Solver to the Analysis of Multielement Airfoils and Wings Using Multizonal Grid Techniques

A computational study was performed to determine the predictive capability of a Reynolds averaged Navier-Stokes code (CFL3D) for two-dimensional and three-dimensional multielement high-lift systems. Three configurations were analyzed: a three-element airfoil, a wing with a full span flap and a wing with a partial span flap. In order to accurately model these complex geometries, two different multizonal structured grid techniques were employed. For the airfoil and full span wing configurations, a chimera or overset grid technique was used. The results of the airfoil analysis illustrated that although the absolute values of lift were somewhat in error, the code was able to predict reasonably well the variation with Reynolds number and flap position. The full span flap analysis demonstrated good agreement with experimental surface pressure data over the wing and flap. Multiblock patched grids were used to model the partial span flap wing. A modification to an existing patchedgrid algorithm was required to analyze the configuration as modeled. Comparisons with experimental data were very good, indicating the applicability of the patched-grid technique to analyses of these complex geometries. ____________________________ *Aerospace Engineer, Aerodynamics Division. Senior Member AIAA. †Aerospace Engineer, Aerodynamic and Acoustic Methods Division. Senior Member AIAA. ‡Student Member AIAA. Copyright © 1995 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under Title 17, U. S. Code. The U. S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Government purposes. All other rights are reserved by the copyright owner. Introduction Many technologies must be successfully integrated in the design of the next generation advanced subsonic transport. Among these are wing design, propulsion integration, design methodology and advanced high-lift systems. As subsonic transport designs get larger and issues such as airport tempo and noise abatement procedures become more important, the design of efficient high-lift systems becomes increasingly more important for improving the take-off and landing phase of the overall airplane mission. Additionally, improvements made in the design of the cruise wings also impacts the design of the high-lift system. Recently developed wing design technology allows designers to develop more efficient wings than those that exist on current subsonic transports. The performance benefits gained by this technology can be used to perform trade studies to improve the overall aircraft system. One way designers exploit these benefits is to reduce the size of the wing (which can help reduce the cost of the aircraft). This reduced wing area means the high-lift system must work even harder to achieve the necessary levels of lift to meet takeoff and landing requirements. More efficient high-lift systems would allow designers to take advantage of these new cruise wing designs. Therefore, the understanding of and ability to analyze these multielement high-lift systems is a problem that must be solved in order to allow the aircraft designer to develop a high-lift system which meets the required performance levels while still designing a wing which is easily integrated into the airplane configuration. Researchers are currently investigating ways to use computational fluid dynamics (CFD) to improve the aerodynamic performance of these multielement highlift systems. The difficulty in understanding and