Numerical simulations of a plasma flow around a membrane-aeroshell type reentry vehicle with various physical models combination were performed and radio frequency blackout for transceiver antenna embedded at the rear of the vehicle was investigated. The flow field was assumed to be thermochemical nonequilibrium and was described by the Navier-Stokes equations with a multitemperature model and the equation of state. The simulations were performed for several altitudes including the highest heat flux point according to a reentry orbit data. Through these computations, flow-field properties distributions in shock layer and wake region were successfully obtained in detail. In order to evaluate the radio frequency blackout during atmospheric reentry, distribution of electron number density around the inflatable vehicle were clarified and the RF blackout possibility was discussed.
In addition, simulations of electromagnetic waves based on the computational results of the plasma flow calculation were performed with a frequency-dependent finite-difference time-domain method. Electromagnetic wave behaviors in an ionized-gas region behind the inflatable vehicle were investigated. It was seen that the number density of electrons was sufficiently small and the electromagnetic waves can propagate with less reflection and attenuation. From these reasons, we found that the RF blackout hardly occurs during atmospheric reentry.
NomenclatureB = magnetic flux density vector, T D = effective diffusion coefficient, m 2 /sec D = electric flux density vector, C/m 2 e = electric charge, C E = electric field vector, V/m f = frequency, Hz J = current density vector, A/m 2 H = magnetic field vector, A/m m = mass, kg n = number density, 1/m 3 S = Poynting vector, W/m 2 t = time, sec T = temperature, K ε r = relative permittivity ε 0 = permittivity in free space, N/V 2 µ 0 = permeability in free space, N/A 2 ν c = collision frequency, Hz σ = conductivity, S/m χ = electric susceptibility