Ning Hu , Cheng Su , Caiqian Yuea
DOI Number XXX-YYY-ZZZ
Conference Number HiSST 2018_2460966
Multi-component flow field and radio blackout effects during the RAM C-II reentry flight are investigated using computation fluid dynamics (CFD) combined with two electromagnetic-wave propagation methods. The flow field is simulated using chemical non-equilibrium Navier-Stokes equation by AUSM+ scheme. The chemical reaction dynamics are simulated using a 7-species-7- reaction and a 11-species-20-reaction models. After electron density is obtained, radio transmission and attenuation are simulated using the Wentzel-Kramer-Brillouin (WKB) and Finite Difference Time Domain (FDTD) methods, for 4 frequency bands, i.e., L-band, S-band, C-band and X-band. Blackout is diagnosed using the criterion that the radio attenuation reaches 30dB. The simulation results are compared with the flight test data. The comparison indicates that the 7-species chemical reaction model cannot correctly predict the electron density in the plasma sheath, while the 11-species model gives good prediction down to the altitude 56.39km, after where the beryllium cap was ejected and the flow started to be polluted by alkali-metal ablation products. FDTD method gives good predictions to radio attenuation and hence to blackout altitude while the WKB prediction of the onset of blackout is earlier than FDTD and flight test results.