Flow Computations Around Delta Wings Using Unstructured Hybrid Grids

Abstract

The capability of an unstructured hybrid grid method to compute the compressible Navier-Stokes equations is discussed for vortical flows over slender delta wings at low subsonic, high-alpha conditions as a basic study of off-design aerodynamics of high speed civil transport configurations. Computations of these flows require high resolutions of the boundary layers on the wing and of the vortical flow region above the wing. The unstructured hybrid grid, which is composed of prismatic grid in boundary layers and tetrahedral and pyramidal grids for the remaining region, is used to treat such viscous flows. The compressihle Navier-Stokes equations are solved on the hybrid grid by a cell-vertex, upwind finite volume method. The lower-upper-symmetric Gauss-Seidel implicit time integration scheme is used for the convergence acceleration to steady state. The numerical accuracy of the present method is discussed by comparing with the experimental data for the same configurations. It is demonstrated that the present hybrid grid method is efficient and accurate enough to predict the vortical flow fields over the delta wings