The application of high-speed monorail rocket sleds to aerodynamic testing at high reynolds numbers.

An LU-SGS(Lower-Upper Symmetric Gauss-Seidel) scheme and improvement for three-dimensional unstructured grid Euler computation are presented.Grid reordering for efficient implementation of the improved LU-SGS and the original LU-SGS is proposed.In order to test the feasibility and efficiency of the improved LU-SGS algorithm,two numerical examples of transonic inviscid flow around an ONERA M6 wing and an LANN supercritical wing are presented.It shows that the numerical results agree well with the experimental data.Moreover,the efficiency of the improved LU-SGS scheme is two times higher than that of the original LU-SGS scheme and seven times higher than that of the explicit Four-Stage-Runge-Kutta scheme.

LU-SGS Scheme and Improvement for Euler Computation on Three-Dimensional Unstructured Grids

Compressor blade design influences aero-engine performance mainly through its total pressure ratio and efficiency. As a volume-based geometric parameterization, Free-form Deformation (FFD) brings three-dimensionality that is essential to blade design. However, the manipulation of control points with respect to simple numeric parametric perturbation renders the use of design space low-efficient. Therefore, an improved FFD with ‘wiser’ control point lay-out is expected to identify those more important design variables. This paper proposes novel design variables that are assigned to grouping of control points’ displacement in FFD lay-out. In short, the approach is realized as: (i) establish a library of sufficient blade shape samples; (ii) filter the database with geometric constraints; (iii) extract dominant modes via (POD) Proper Orthogonal Decomposition; (iv) construct new design variables and apply them in optimization. With geometric constraint filtering, problem-oriented information is injected. With POD, the dominance of new selected geometric parameters in problem description is assured. Perfunctory details of displacement data of each control point in the lay-out can be replaced by grouped data as new design variable candidates. As a proof-of-concept study of the new approach, compressor blade Rotor 37 is selected to be the good platform of testing the feasibility of POD-aided FFD as a global and flexible yet economic geometric parameterization. Result demonstrates the feasibility of proposed POD-aided FFD approach that helps conduct an optimization involving displacement of 6 × 4 × 3 control points with as few as five new design variables, while still being capable of bringing optimization effect in three test cases.

An approach of Proper Orthogonal Decomposition-aided Free-form Deformation with application in compressor blade design

Convergence rates of the original LU-SGS scheme and its modified methods were investigated and compared under hypersonic conditions,which is aimed to implement the LU-SGS algorithm efficiently for numerical simulation of complex geometries in engineering environment.Numerical results of 2D cylinder,3D blunt cone and space shuttle show that: the viscous terms must take the implicit form for hypersonic viscous flows.the convergence rate of the BLU-SGS inner iterations is fast than that in the DP-LUR method.Jacobian matrices in the LU-SGS algorithm have a significant effect on computational work and convergence performance.for the flows without separation,fast convergence can be reached by using the exact matrix method and for the flows with large separation,numerical instability makes the exact matrix method less efficient than the diagonal method.

Application of the implicit LU-SGS algorithm for hypersonic flows

An aerodynamic design optimization of a hypersonic rocket sled deflector is presented using the free-form deformation (FFD) technique. The objective is to optimize the aerodynamic shape of the hype...

Dike Hu

Papers

Aerodynamic design optimization of a hypersonic rocket sled deflector using the free-form deformation technique