Junhyeon BAE, Jukyoung SHIN, Tae Young KIM
DOI Number: N/A
Conference number: HiSST-2025-167
Effective thermal protection systems are critical for the viability of reusable space vehicles enduring extreme atmospheric re-entry heating. Among active cooling strategies, transpiration cooling using liquid coolants is particularly promising, but its performance is complicated by internal phase-change phenomena. This study presents a numerical investigation into coupled thermo-hydrodynamics within porous media, aiming to elucidate the underlying complex mechanisms of phase-change transpiration cooling. A high-precision numerical model, validated with existing literature, was developed to systematically analyse the effects of various heat fluxes and coolant mass flow rates on system
performance. The steady-state results demonstrate that the system’s thermal and hydrodynamic characteristics are intricately linked to the location of the internal phase change. The instability of phase-change cooling systems is identified, wherein the sharp decrease in average kinematic viscosity due to reduced vapor fraction outweighs the effect of increased mass flow rate, resulting in reduced pressure drop as flow rate increases. Temperature distribution analysis revealed steeper temperature gradients in the vapor region compared to the liquid region due to lower thermal conductivity, with pronounced local thermal non-equilibrium effects in the two-phase region.