Bionic phase-change transpiration cooling structure for morphing flight: Heat-mass transfer mechanism and modeling

Next-generation space transportation systems exhibit advanced technical features, including trans-atmospheric flight, broad speed regimes, reusability, and intelligent operation. However conventional rigid thermal protection systems are constrained by limited deformation capabilities, preventing them from simultaneously fulfilling thermal insulation and structural morphing requirements under high-temperature and large-deformation scenarios. To address this challenge, an adaptive-self-driven flexible phase-change transpiration cooling structure was proposed, inspired by the fractal transport pathways of leaf venation. This design integrated the large-strain capacity of flexible materials with capillary-driven microchannel mechanisms, achieving efficient and uniform cooling performance. Ground thermal testing under moderate heat flux conditions (170 kW/m²) demonstrated the structure's self-driving capability and cooling efficiency, with surface temperatures maintained below 130°C, validating the feasibility of phase-change transpiration cooling. A coupled heat and mass transfer model was developed by integrating surface tension theory in microchannels with liquid-gas-solid multi-phase heat transfer mechanisms, quantifying the influence of geometric parameters (e.g., channel diameter and branching angles) on cooling effectiveness. Model predictions aligned well with experimental data (error <10%), providing theoretical support for the parametric design of flexible phase-change cooling structures. The correlation between structural deformation range, temperature response, and coolant consumption under representative morphing scenarios was systematically analyzed. Results showed that surface temperature fluctuations remained <5%, while coolant flow responses exhibited nonlinear characteristics, highlighting the structure's robust dynamic regulation capacity and offering new insights for flexible TPS design. This work provides an innovative technical pathway for thermal protection system design in next-generation morphing aerospace vehicles, enabling reliable operation in extreme high-temperature and structural deformation environments.