Finite Element Methodology for Integrated Flow-Thermal-Structural Analysis

Abstract

Thermal deformations and stresses induced by aerodynamic heating are important considerations in the design of hypersonic flight vehicles. Aerodynamic heating has a significant effect on the performance of the structure, and effective techniques for predicting the heating rates and thermal-structural response are required. In the past, the heating and thermal-structural analyses have typically been uncoupled. Structural heating rates have been computed for viscous flows over undeformable aerodynamics surfaces with prescribed thermal boundary conditions. In realistic high speed flows, aerodynamic surfaces deform as a result of the thermal loads, and thermal conditions are not constant at the fluid-structure interface. During the aerodynamic heating of a structure the fluid-structure interface deforms, and the structure continuously absorbs thermal energy from the flow. These interaction effects may in fact alter the heating rates to the structure. In [1–2], experiments and analyses conducted at the NASA Langley Research Center show that actual heating rates experienced by metallic thermal protection systems can be significantly higher than rates based on undeformed flat plate computations. For example, for deformed heights less than the boundary layer thickness, heating rates can be increased by as much as 40 percent; moreover, heating rates increase rapidly when deformed heights exceed the boundary layer thickness.