A fully implicit Lower-Upper-Symmetric-Gauss-Seidel (LU-SGS) with pseudo time sub-iteration and the modified Jameson's central scheme are applied to solve thin layer Navier-Stokes(N-S) equations with laminar hypothesis and Baldwin-Lomax(B-L) model for the vortical flows around delta wings at high angles of attack (AOA).To validate the codes,a 65 degree swept delta wing is computed in transonic cases,where M_∞=0.85,α=10°,20° and Re=5×10⁶.Then asymmetrical vortex breakdown flows with M_∞=0.3,and Re=1.3×10⁶,at high AOA around an 80° swept delta wing are presented and discussed.The computational results are compared with experimental data available and good agreement is achieved.

A multi-layer hybrid grid method is constructed to simulate complex flow field around 2-D and 3-D configuration.The method combines Cartesian grids with structured grids and triangular meshes to provide great flexibility in discretizing a domain.It generates the body-fitted structured grids near the wall surface and the Cartesian grids for the far field.In addition,the triangular meshes are regarded as an adhesive to link each part of grids.The grid combination methodology is discussed,which can smooth hybrid grids and improve the quality of the grids.A uniform type of data is defined to manage and arrange grid data.Using the centered finite volume method,the inviscid and viscous flow allows computation by solving the Euler and Navier-Stokes equations.The computational results prove that grid generation and flow calculation are correct and feasible.

Four turbulence models:algebraic Baldwin-Lomax model with Degani-Schiff modification, two versions of Johnson-King model (J-K90A and J-K92) and two-equation k-g model, are described and evaluated for missile supersonic flow, NASA TN D-712 standard model and the civil airplane wing-body configuration (two-block C-O mesh) transonic flows. The 3-D compressible Reynolds averaged Navier-Stokes (RANS) equations are integrated numerically by central-difference with artificial viscosity scheme, finite volume formulation and explicit multi-step Runge-Kutta algorithm. The turbulence equations of k-g model are explicitly solved in the same way as the RANS. Results show that all models can perform well for attached and mildly separated flows. For large angle-of-attack separated flow over the missile, k-g and J-K92 models match the experimental results much better than those with B-L and J-K90A models. According to the B-L model with some modification, the shock location logs behind those with the other three models for the civil airplane geometry. Model k-g, because of its advantages such as without using normal-to-wall distance, simple source terms and straightforward boundary conditions, performs best in the four models for complex configuration with multi-block mesh system or multi-wall interference. B-L and J-K models, despite of cheapness and robustness, both base on empirical Prandtl mixing-length hypothesis and need to calculate the distance normal to the wall, undoubtedly limiting the application scope of these models for multi-block mesh system and complex geometry.

A method for the adaptive refinement of a Quad/Cartesian grid for the solutions of the Euler and N-S equations is presented.An adaptive Quad/Cartesian hybrid grid method,which retains the advantages of the Cartesian grid approach and, at the same time, touches the viscous flow problems,is provided.The body fitted Quad grids are generated around the body and the Cartesian grids are used in the remains of the flow field.The flow solver of the Euler and N-S equations is performed by a conventional algorithm,including the finite volume method and the Runge-Kutta time-stepping scheme.The grid adaptation and the flow solver achieve reasonable efficiency and accuracy with minimum computer resources.Based on the above approach,the numerical analysis of flows around the single-element and the multi element airfoils is given.The numerical results presented show the flexibility of this approach and the accuracy attainable by the solution-based refinement.

Grid generation and flow analysis methods for multi-element airfoil based on multi-block point-to-point patched grid technology are developed. Some strategies are developed to improve the efficiency, accuracy and applicability of the method.Several flow cases about multi-element airfoils are computed with the present method in order to validate it. Numerical results are in agreement with experiment data. Flow field visualization shows that the present method has good resolution in flow details.

A new unstructured Cartesian cutted grid generation method is introduced. The grid generation of some airfoils and wing is performed with the tree data structure. Euler equations are solved using the cell-centred finite volume method. The results of flow field computation are in agreement with the experiments. These facts show that the grid generation and the numerical calculation approach is correct and reasonable. Based on the above work, a flow field numerical simulation of wing and store separation is finished. This process provides a new way and tool for the more accurate solver of the unsteady flow problem.

Because of the complexities in both configurations and flow phenomena,there are great difficulties in the numerical simulation of flow about wing with lift-enhancing devices and control surfaces.By using cell-centered finite volume method,it deals with Renolds-averaged Navier-Stokes equations on multi-block structural grids generated by elliptic method.Two kinds of patching schemes,point-to-point and patch-on-common-surface,are employed to establish the information exchange among blocks.In the later one,the overlap cell area weighted interpolation is used to guarantee the conservation.Ramshaw algorithm is also used to pre-determine the overlap areas.Flow fields about multi-element airfoils and delta wing with deflected flap are computed with the present method.Numerical results are all in good agreement with experiment data.Flow field visualization shows the present method has good resolution in flow details.