Dissimilar material association analysis of thermal response in functionally graded thermal protection structures for high-speed flight experiments

Obtaining valid thermal data and evaluating the thermal protection performance of functionally graded materials (FGMs) under flight conditions are the keys to their engineering application in high-speed vehicle thermal protection. To obtain the aerothermal loads and response data of FGMs, this paper proposed a dissimilar material association analysis method of thermal response in functionally graded thermal protection structures under flight conditions. A flight experiment at high Mach numbers carrying FGMs was conducted partially to demonstrate this thermal response analysis method in real flight conditions. Control-panel-based data processing was carried out to obtain aerodynamic thermal loads applied to the test panel where the novel carbon-based FGMs are located. Based on the dissimilar material association analysis method, numerical reconstruction of the inhomogeneous heat transfer in FGMs at high speeds was obtained and compared with measured data from spatially layered sensors. The comparison with flight experimental data shows that the reconstructed temperatures both on the surface and inside the FGMs are consistent in trend with the flight measurements. Quantitatively, the reconstructed temperatures are 6.08 % and 8.07 % higher than the in-flight measured value at the peak temperature point of the ascent and descent trajectory, respectively. This flight experiment and post-flight dissimilar material association analysis examine the novel FGMs, providing first-hand data for the engineering application of these integrated composite materials in near-space high-speed vehicles.