Analysis of weakly ionized ablation plasma flows for a hypersonic vehicle

Hypersonic vehicles are enveloped by a plasma sheath that affects the data transmission and object identification. This paper develops a numerical methodology based on Magnetohydrodynamics equations to study the electromagnetic environment of hypersonic vehicles under the condition of carbon-based thermal protection material ablation. A surface ablation model considering the oxidation and sublimation ablation process is coupled with a Navier–Stokes solver by a gas–solid interaction method to simulate the ablation plasma flows. A piecewise linear current density recursive convolution finite-difference time-domain method is applied to further analyze the interaction between the incident electromagnetic wave and the plasma sheath. The computational results for an HTV-2 type vehicle indicate that both ablation and non-ablation plasma sheaths have significant effects on the electromagnetic environment of the vehicle. Compared with a non-ablation plasma sheath, ablation results in a decrease in the number of electrons and increases the number of neutral particles and therefore changes characteristic parameters of the plasma. Details of the electromagnetic scattering characteristics are reported to highlight the influences of ablation on the reflectivity, penetrability, and absorptivity of the plasma sheath for incident electromagnetic waves over different bands.