Research On Preconditioning Method And Application To Flight Vehicle Design

In this thesis, a preconditioning method is investigated and a flow field solver by solving three-dimensional Navier-Stokes (N-S) equations on hybrid grids is developed. The viscous flow around NACA0012 airfoil and a low-aspect-ratio wing of CLARK Y are simulated and compared with the results of wind tunnel experiment.Method of mesh generation is improved daily and function of grid generation software is unceasingly perfect. Mesh generator Gridgen is applied to generate two-dimensional structured meshes and three-dimensional unstructured viscous meshes. Not only many high quality meshes are constructed but also those meshes are applied in actual numerical simulation and computation.In this thesis, a preconditioning technology is expanded into solving the unsteady compressible N-S equations, and an effective numerical method for simulating three-dimensional steady low-speed flow fields is developed. Governing equations based on the Reynolds-averaged Navier-Stokes equations are solved using the cell-centered finite volume spatial discretization and LU-SGS time-stepping scheme on hybrid viscous grids with standard convergence acceleration techniques such as local time stepping and implicit residual smoothing. The Spalart-Allmaras one-equation turbulence model is used to simulate turbulent-flow problem. Based on the above work, the preconditioning method can apply the time-marching schemes solving the compressible N-S equations to the low-speed flow. The computed results indicate the methods combined the preconditioning method and compressible N-S are efficient to solve the low-speed flow.Finally, using the flow solver developed by this thesis simulates the low-speed flow field of the wing of Micro air vehicles with different plain forms, and analyses their aerodynamic performance.