Experimental Study on Thermal Protection Performance of an Insulation-dissipation Structure

Hypersonic vehicles experience sustained and spatially distributed aerodynamic heating usually. For the thermal protection of large-area regions of vehicles,conventional passive systems only delay heat conduction and cannot suppress heat accumulation during prolonged heating. In this study, an insulation-dissipation thermal protection structure is proposed, integrating an external multilayer insulation with an internal membrane-based dissipative evaporation layer to achieve both heat attenuation and active heat dissipation. An experimental setup is established to simulate high heat flux conditions using flame-heating, where a ceramic insulation layer and an aerogel insulation layer are coupled with a water-membrane evaporator. The dynamic thermal responses are investigated under different heat fluxes and ambient pressures. The results indicate that the external insulation layers effectively attenuate the imposed heat flux and the internal dissipative evaporation layer significantly reduces the temperature rise of the hot wall, via absorbing heat through phase change without disturbing the insulation performance. The structure exhibits a self-regulating thermal response characterized by quasi-steady operation and intermittent temperature perturbations arising from unsteady evaporation under sustained heating. Lower ambient pressures promote stronger but unsteady evaporative cooling, whereas higher pressures lead to elevated temperatures and weakened evaporation. Furthermore, mini-channels fabricated on the inner wall of the water cavity enable spontaneous liquid redistribution driven by capillary forces, effectively reducing hot-wall temperature, and markedly improving temperature uniformity by about 15%, especially under high heat flux conditions. Membrane pore diameter shows limited influence on dissipative evaporation when porosity is constant.