Numerical prediction of plasma formation on a sphere in hypersonic sub-orbital flight regime

Hypersonic flight is challenging for vehicle design and operation due to the intense heating generated by kinetic energy transfer from the vehicle to the gas surrounding it. As a result, plasma is produced, which can interfere with radar tracking and communication, particularly upon re-entry into the Earth’s atmosphere. Plasma affects wave propagation, and if the electron density is high enough, waves may lose intensity as they propagate, distorting radar traces. The objective of this research is to predict plasma formation during suborbital hypersonic flight, with a specific focus on determining the Mach number and altitude conditions that generate critical levels of plasma density. To achieve this, Computational Fluid Dynamics is employed to solve the Navier-Stokes equations, and a multi-temperature thermochemical model is adopted to accurately predict plasma behavior. The model is applied in a simplified scenario involving a sphere exposed to hypersonic flow.