Unsteady Heat Transfer for Pressure Vessels in Atmospheric Flight at Orbital Velocities

Abstract

Aeroassisted trajectories can be used to minimize spacecraft propellant requirements for near-Earth orbital operations. A review of spacecraft flight mechanics, aerothermodynamics, and energy balances relevant for near-term designs of reusable upper stages is presented. A reusable upper stage is modeled by a rigid tank containing liquid propellant with some propellant fraction undergoing phase change, while in an a planar aeroassist trajectory about an idealized Earth. Shortcomings of classical analyses are illustrated to motivate models with increased fidelity and complexity. A new method is proposed and models the material response of the spacecraft under aerothermal loading, that couples the simplicity of classical methods with a three-dimensional scheme that captures unsteady thermal gradients in the material. The new method is shown to provide similar solutions to a fully discrete case with a significant reduction in computational time.