Numerical investigations of transpiration cooling of N2-He binary mixture in hypersonic laminar flow

Transpiration cooling effectively mitigates heat transfer on hypersonic vehicle surfaces, yet optimizing the coolant reservoir volume remains a significant design challenge. Although helium provides exceptional cooling efficiency, its use necessitates larger storage volumes compared to heavier gases. In this study, we investigate a binary helium-nitrogen mixture to minimize reservoir size while achieving optimal thermal performance. Employing two-dimensional numerical simulations based on kinetic theory and an ideal gas mixture model, we attained an average thermal effectiveness of unity and reduced the coolant reservoir volume to 285 cm3-a 78.5% decrease relative to pure helium. The optimal gas mixture, containing 8% helium and 92% nitrogen, offers a promising solution for enhancing both efficiency and space utilization in hypersonic vehicle designs.