Hybrid Computational Model for High-Altitude Aeroassist Vehicles

The proposed effort addresses a need for accurate computational models to support aeroassist and entry vehicle system design over a broad range of flight conditions including direct entry and aerocapture trajectories for manned and unmanned earth return and planetary exploration. These models are critical for assessing aerodynamic characteristics including reaction control systems (RCS) influences and for designing thermal protection systems involving both ablating and non-ablating materials. A hybrid approach unifying continuum CFD and rarefied DSMC flow solvers will be developed that can handle both higher altitude continuum flows, i.e. 60~85km, with embedded rarefied zones such as the base/near-wake region as well as higher altitude rarefied flows with embedded continuum zones such as RCS jet plumes. The proposed model will automatically separate continuum and rarefied regions into distinct computational domains employing a unique methodology demonstrated in Phase I to construct hybrid interface surfaces for complex three-dimensional geometries. The model will incorporate RCS jet and advanced ablative models and will provide consistent nonequilibrium thermochemical modeling between the CFD and DSMC solutions. This methodology provides a more efficient and accurate tool than provided by continuum CFD or DSMC alone and provides the flexibility to address a wide range of vehicle and system designs.