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

Abstract

An analysis model of plasma flow and electromagnetic waves around a reentry vehicle for radio frequency blackout prediction during aerodynamic heating was developed in this study. The model was validated based on experimental results from the radio attenuation measurement program. The plasma flow properties, such as electron number density, in the shock layer and wake region were obtained using a newly developed unstructured grid solver that incorporated real gas effect models and could treat thermochemically non-equilibrium flow. To predict the electromagnetic waves in plasma, a frequency-dependent finite-difference time-domain method was used. Moreover, the complicated behaviour of electromagnetic waves in the plasma layer during atmospheric reentry was clarified at several altitudes. The prediction performance of the combined model was evaluated with profiles and peak values of the electron number density in the plasma layer. In addition, to validate the models, the signal losses measured during communication with the reentry vehicle were directly compared with the predicted results. Based on the study, it was suggested that the present analysis model accurately predicts the radio frequency blackout and plasma attenuation of electromagnetic waves in plasma in communication.

Aerodecelerator Performance of Flare-Type Membrane Inflatable Vehicle in Suborbital Reentry

“…Generally, because effective CFD algorithms for supersonic flow (compressible) and subsonic flow (incompressible) are largely different, it is desirable to use solvers suitable for the compressible and incompressible flows from the viewpoint of computational cost and accuracy. In the present study, RG-FaSTAR v2.0.0 [23] for the supersonic flow region and FrontFlow/red (FFR) Ver.3.1 [24] for subsonic flow are adopted, respectively. RG-FaSTAR is a high-enthalpy flow solver that incorporates real gas effects and thermochemical nonequilibrium and is a version of the fast unstructured CFD code FaSTAR [25], originally developed by JAXA.…”

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

“…Physical model and numerical method used in this plasma flow simulation are basically the same as those used in Takahashi's work [5], except for part numerical scheme and calculation conditions. Here, brief explanation about the present plasma flow model are presented.…”

“…These physical and numerical models are implemented in the high-enthalpy flow solver RG-FaSTAR [5]. RG-FaSTAR is a version of the fast unstructured CFD code FaSTAR [28] originally developed by JAXA that incorporates real gas effects.…”

“…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].…”

“…Thus, it is worth investigating the distributions of plasma and electromagnetic waves for design and development of new reentry vehicles and for research and development concerning RF blackout mitigation techniques. Takahashi [5] recently developed an RF blackout prediction tool combining RG-FaSTAR, which is a high-enthalpy flow solver applicable to unstructured grid systems, and FD2TD simulation code. Using the analysis models, it is possible to investigate the behavior of electromagnetic waves in reentry plasma.…”