Multiple Oxide Species Formation Along a Hypersonic Leading Edge Utilizing Transpiration Cooling

Thermal protection systems (TPSs) are essential for managing the large incident heat fluxes experienced by hypersonic aircraft. The state-of-the-art in TPS technology is limited in shape and reusability due to surface degradation. Evaporative transpiration TPSs can protect sharp leading edges without experiencing surface degradation. Previous studies have shown that these TPSs are capable of cooling incident heat fluxes of [Formula: see text], but that coolant oxidation can increase the required coolant mass flux by a factor of 2. Additional oxide species may form due to oxygen deprivation in the flow, exacerbating this concern. This study investigates the effect of additional oxide species formation using three-dimensional direct numerical simulation algorithms that consider thermochemical nonequilibrium flow at Mach 15 and 30 km altitudes along a 3.1 mm nose-tip radius. The formation of additional oxide species increases the required coolant mass flux by a factor of 3.6. Reactions favoring dissociation of oxides still increase the coolant mass flux by a factor of 1.44. An expression is derived to assist in coolant material selection considering coolant oxidation. These results help to inform coolant selection for the future design of evaporative transpiration TPSs.