Methane phase-change transpiration cooling performance in hydrophobic/hydrophilic porous structure

Phase-change transpiration cooling is a promising thermal protection technology for spacecraft. It is essential to identify the critical flow rate to balance system weight constraint and high cooling performance demand. Pore-scale heat and mass transfer phenomena are significant for predicting the migration of the phase-change interface and the critical flow rate, where wettability exerts a strong influence. In this paper, based on a hybrid thermal lattice Boltzmann method, the transient characteristics and thermal failure behaviors of methane phase-change transpiration cooling are explored. Comparative analysis of liquid–gas interface evolution between hydrophobic and hydrophilic structures is conducted under different flow rates. Additionally, their respective cooling performance is quantified at the range of Re = 0.28–1.40. The results indicate that in the phase-change zone, wettability affects the liquid-gas interface morphology, thereby influencing the cooling performance. At Re = 0.28, the vapor film continuously permeates into the porous structure, hence causing temperature rise and thermal failure. When the flow rate exceeds critical value (Re = 0.84), a continuous liquid film is observed at the outlet of hydrophilic porous structure, achieving better temperature uniformity than that of the hydrophobic structure and effectively eliminating the thermal failure. Compared to the hydrophobic structure, the hydrophilic structure achieves an average temperature reduction of 7.89% and an improvement of 10.21% in the comprehensive evaluation factor at Re = 1.40. Meanwhile, cooling efficiency is dominated by flow rates rather than wettability. This study provides a theoretical basis for the optimized design of next-generation transpiration cooling thermal management.