Examination of Radio Frequency Blackout for an Inflatable Vehicle During Atmospheric Reentry

Abstract

Numerical simulations of the plasma flow and electromagnetic wave around a membraneaeroshell type reentry vehicle were performed using various physical model combinations, and the possibility of radio frequency blackout of transceiver antenna embedded at the rear of the vehicle was investigated. The flow field was assumed to be in thermochemical nonequilibrium, and it 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 reentry orbit data. Through these computations, the detailed distributions of the flow-field properties in the shock layer and wake region were successfully obtained. To evaluate possibility of the radio frequency blackout during atmospheric reentry, the distribution of the electron number density around the inflatable vehicle was clarified. A frequency-dependent finite-difference time-domain method was used for simulations of electromagnetic waves, and the physical properties were obtained from the computational results of the plasma flow calculation. Electromagnetic wave behaviors in an ionized gas region behind the inflatable vehicle were investigated. It was found that the number density of electrons was sufficiently small and that the electromagnetic waves can propagate with less reflection and no attenuation. These results suggest that radio frequency blackout may not occur during the atmospheric reentry of the inflatable vehicle.

Advanced validation of CFD-FDTD combined method using highly applicable solver for reentry blackout prediction

“…A formulation for the thermochemical non-equilibrium plasma flow during the aerodynamic heating was constructed, and its numerical implementation was achieved using the high-enthalpy flow simulation code RG-FaSTAR, which was developed according to the fast unstructured CFD solver "FaSTAR" [13] manufactured by JAXA. For an electromagnetic-wave simulation in plasma around reentry vehicle, the FD2TD method [8,12] was used. The distributions of plasma properties obtained by the flow solver were transposed on the computational domain for the electromagnetic-wave simulation, and the behaviour of electromagnetic waves in plasma around the reentry vehicle was clarified.…”

“…Because the FD2TD method with the first Drude dispersion used in the present study was formulated by Takahashi et al [8,12], physical and analytical models are briefly described in this section.…”

“…Belov et al [6] investigated an aerodynamic shaping technique to alleviate the RF blackouts by mounting slender nosecone probes, containing a communication antenna, ahead of a blunt nose vehicle. Takahashi et al [7,8] suggested that an inflatable vehicle with a low ballistic coefficient and a large projected area for deploying its flare aeroshell in orbit can reduce the RF blackout. Thus, it may be possible for a vehicle with such features and devices to communicate without RF blackouts during a reentry mission.…”

Prediction Performance of Blackout and Plasma Attenuation in Atmospheric Reentry Demonstrator Mission

“…In fact, it was suggested in Ref. [1,2] that an inflatable vehicle passively reduces the RF blackout with a data-relay satellite during atmospheric reentry on account of its low-ballistic coefficient flight and distinctive vehicle configuration. Moreover, an RF blackout mitigation method that uses a magnetic field has been investigated [3].…”

Numerical Analysis of Radio Frequency Blackout for Atmospheric Reentry Vehicle Using CFD-Cem Combined Method

“…In particular, the frequency-dependent finite-difference time-domain (FD2TD) method [1] has also been an effective tool for simulating electromagnetic waves in a frequency-dependent medium [2]. An analysis approach to predict RF blackout and plasma attenuation for a reentry vehicle, based on a method combining CFD and CEM, has been suggested by Takahashi et al [3,4,5].…”