Characterization of hypersonic flow over slender bodies at sea-level

Historically, aerothermal analyses of hypersonic vehicles have been performed assuming a dry-air atmosphere because these vehicles were designed to fly at high altitudes. Modern hypersonic vehicles may fly at sea level, exposing them to humid air atmospheres. The presence of water vapor could affect the aerothermal environment around hypersonic vehicles, in turn affecting the performance of their heat shields and propulsion systems. To study the impact of water vapor on the aerothermal environment and aeroheating, Mach 10 flows over the high-speed Army Reference Vehicle (HARV) is computed at altitudes of 0 and 10 km with varying molar fractions of water vapor. It is observed that with the increase in water vapor levels, the shock distance and temperature ratio across the shock are decreased. At both altitude conditions, supralinear depression of atomic oxygen appears to result from aerothermochemical coupling with introduced hydrogenous species. To study how a carbon surface would interact with the humid air environment, the surface stagnation point composition is explored using gas-surface equilibrium. Under present assumptions, stagnation point mass flux rates at the surface seem to be affected by the presence of water vapor. Primarily, water vapor provides a cooling effect but species composition predictions are not altered by the presence of water vapor. At 10 km altitude, the relationship between stagnation point mass flux and water vapor presence is much weaker.