Conjugate Heat Transfer Analysis of Hot Structures
Figure 1: Schematic Diagram for Four-Field Computational Framework
High temperature gas-effects are predominant in hypersonic flows. Solving the heat-transfer problem is then critical to well predict the peak temperature and peak heat transfer to design thermal protection.

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Sebastien Brogniez

At hypersonic temperature, significant coupling occurs between the flow and the structure. Tests conducted in the Mach 7 High-Temperature Tunnel at NASA Langley Research Center showed that panels bowed-up into the flow to produce heating rates that are up to 1.5 times greater than flat-plate prediction. Scramjet unstart has often been observed at NASA simply because of important structural deformations. The same phenomenon has also been observed during the development of the Hypersonic Commercial Transport.

With the complexity of phenomena occurring at hypersonic speed, a fully integrated fluid/structure code is unreasonable. The idea is then to use a staggered scheme which will take advantage of using already-existing state-of-the-art fluid codes and structural codes. For the aerothermal component, surface temperature and heat transfer are exchanged between the CFD code and the thermal analysis code. For the aeroelasticity part, the stress at the interface and the displacement of the interface are exchanged between the CFD code and the Structure code via a Dynamic Fluid Mesh solver (see Figure 1).

Stability and accuracy of this procedure have to be considered. This will lead to a four-field computational framework capable of capturing aerothermoelastic effects.