Development of a rapid inviscid-boundary layer aerodynamics tool

Hypersonic vehicles, combined with scramjet propulsion, offer significant and unique flexibility, performance and reusability benefits over rockets. These characteristics will likely reduce the cost of access-to-space. However, the realisation of such vehicles is significantly complicated by engine performance requirements which dictate relatively low altitude, high dynamic pressure trajectories. The thick atmosphere and high velocities result in high aerodynamic drag and heating. This paper introduces a simple, aerothermodynamic model for the analysis of hypersonic vehicles using Cart3D to calculate the inviscid flow-field and provide edge conditions to boundary layer calculations. Comparisons are made between two viscous methods of varying fidelity; flat plate correlations for skin friction with a simplified running length calculation and integral methods applied along inviscid, surface streamlines. Three validation cases are presented; (1) a hypersonic, blunt body; (2) a delta-wing, lifting body at subsonic to hypersonic Mach numbers and (3) a hypersonic, realistic vehicle configuration with internal flow-paths. In general, Cart3D predicts the lift and pitching moment coefficients well but consistently under-predicts drag given the absence of shear stress. The viscous contribution to aerodynamic forces was found to be adequately modelled using flat plate correlations and a simple Euclidean distance in place of the true running length. Preliminary results, however, suggest predictions of surface heat transfer rates benefit from a streamline running length and higher fidelity boundary layer methods