Thermal analysis and design optimization of multilayer insulation for reentry aerodynamic heating

A design-of-experiment technique was used to investigate optimum design of multilayer insulations for reentry aerodynamic heating. Combined radiation/conduction heat transfer in high-temperature multilayer insulations was modeled using a finite volume numerical model, which was validated by comparison with steady-state effective thermal conductivity measurements, and transient thermal tests simulating reentry aerodynamic heating conditions. It was found that use of 2-mm foil spacing and locating the foils near the hot boundary, with the top foil 2 mm away from the hot boundary, resulted in the most effective insulation design. A 76.2-mm-thick multilayer insulation using 1, 4, or 16 foils resulted in 2.9, 7.2, or 22.2% mass per unit area savings, respectively, compared to a fibrous insulation sample at the same thickness.