Pore-Scale flow and conjugate heat transfer in heterogeneous porous Media: Vortex dynamics and thermal management implications

Efficient thermal protection is crucial for high-speed aircraft exposed to extreme aerodynamic heating. Active cooling using porous media has emerged as a promising solution due to its high surface-to-volume ratio and strong convective capacity. In this study, pore-scale numerical simulations are conducted in randomly generated heterogeneous porous structures (porosity 0.4–0.9) to investigate coupled flow and heat transfer characteristics across both Darcy and non-Darcy regimes. The model accounts for conjugate heat transfer, vortex dynamics, and nonlinear inertial effects under a constant inlet mass flux ranging from 0.1 to 6.5 kg/(m²·s). Results show that vortices preferentially emerge in pore-throat expansion zones, with stability duration strongly dependent on porosity. An increased mass flux enhances vortex strength but simultaneously reduces effective permeability due to the occupied flow volume. Heat transfer analysis reveals that average temperature decreases significantly with rising mass flux, but with diminishing returns beyond 4.5 kg/(m²·s). Thermal resistance remains below 0.8 K/W across all operating conditions, which confirms the excellent thermal regulation capacity of porous convection cooling. Furthermore, the Peclet number increases sharply when porosity exceeds 0.7, indicating convection-dominated heat transfer at higher porosities. The findings clarify pore-scale transport mechanisms and provide design guidelines for thermal protection systems utilizing porous media.