ASSESSMENT OF THERMOCHEMICAL NONEQUILIBRIUM AND SLIP EFFECTS FOR ORBITAL REENTRY EXPERIMENT

Results are provided from a viscous shock layer (VSL) analysis of the re-entry flowfield around the forebody of the Japanese Orbital Re-entr y Experiment (OREX) vehicle. This vehicle is a 50-deg spherically blun ted cone with a nose radius of 1.35 m and a base diameter of 3.4 m. Ca lculations are performed for the OREX trajectory from a 105 to 48.4 km altitude range. A seven-species chemical model for air is found adequ ate for the flowfield analysis. However, for altitudes greater than 84 km, the low-density effects (such as thermal nonequilibrium and slip) must be implemented to accurately predict flight-inferred heat transf er rate data. At altitudes lower than 84 km, a finite surface recombin ation probability employed in place of a noncatalytic surface enhances the agreement between the calculations and flight data. VSL results a re also compared with the direct simulation Monte Carlo predictions at high altitudes (>80 km) and the electron number density data for thre e altitudes in the OREX trajectory. Overall, the agreement between the flight data and calculated results is quite good.