High-Fidelity Material Response Modeling as Part of an Aerothermoelastic Framework for Hypersonic Flows.

Abstract

The development of a numerical code capable of simulating the multidimensional thermal and structural response of materials exposed to hypersonic flow is presented. The control volume finite element method (CVFEM) is used for spatial discretization, and implicit time integration is used in both the thermal and structural portions of the code. Fourier's law is used to compute heat fluxes, and the thermal portion of the code can model materials with temperature-dependent, anisotropic properties. A total Lagrangian structural mechanics formulation is used along with the Green-Lagrange strain tensor and the generalized Hooke's law, to allow for simulation of large elastic deformations of temperature-dependent, orthotropic materials. The Method of Manufactured Solutions (MMS) is used to verify the implementation of several aspects of the material response code.

The material response code is coupled with a Computational Fluid Dynamics (CFD) code using a partitioned framework, in order to study quasi-static aerothermal and aerothermoelastic problems that arise in hypersonic flow. Characteristic times for the flow component of the coupled problem are assumed to be much faster than the thermal and structural time scales, allowing for steady state flow solutions to be used. The thermal and structural material response is updated as the flow solution converges to steady state. The temperature solution is used to compute thermal stresses in the structural response. The MMS is used to verify the CFD code and some aspects of the coupling procedure.

Two test cases are presented to demonstrate the performance of the material response code and the coupling framework. The first case simulates the aerothermal response, including surface ablation, of a reentry vehicle. Comparisons are made with results from other codes, and it is found that accounting for multidimensional heat transport within the vehicle leads to higher surface temperatures, but lower surface recession. The second test case models a thermally insulated compliant panel in an hypersonic flow. A strong dependence on the time between computing updated flow solutions exists, even for cases that are dynamically stable. Additionally, dynamic panel response is observed for some test conditions, and the impact of this behavior on the quasi-static coupling framework is discussed.