Finite element modeling and optimization of high-speed aerothermoelastic systems.

摘要

The design of supersonic and hypersonic aerospace vehicles is by nature a multi-disciplinary problem requiring the close integration of compressible fluid dynamics, heat transfer, and structural dynamics. The transient flow around the body must be accurately characterized in order to assess its affect on the thermal and structural responses; conversely, the thermal and structural behavior may significantly alter the aerodynamic performance. The core of this dissertation effort is concerned with the development and demonstration of an analysis and design capability for the aerothermoelastic behavior of high-speed aerospace vehicles. This nominally involves coupling of the compressible Navier-Stokes equations for the fluid dynamics, the transient heat equation for the thermal response, and the elastodynamic equations for the structural dynamics. The streamline upwind Petrov-Galerkin (SUPG) stabilized finite element method is used for solving the compressible flow problem. Both a standard Galerkin and stabilized Galerkin gradient least squares (GGLS) finite element method are utilized for solving the heat equation, and a standard Galerkin method is used for solving the elastodynamic equations. The transient and steady-state responses of a problem are determined via a single, simultaneously coupled nonlinear system, thus bypassing accuracy and stability issues of classical staggered multi-physics coupling strategies. A gradient-based optimization framework is developed for designing transient coupled aerothermoelastic systems via adjoint-based sensitivity analysis. This framework is used to optimize the design of a structure in regard to thermal and structural performance. The efforts of this thesis have yielded a state-of-the-art approach for coupled aerothermoelastic analysis and design optimization.