Study By Simulation Of Supersonic Flows And Blackout Mitigation

Spacecraft flying in supersonic velocities(above 5 mach) in atmosphere normally encounters the communication interruptions. The interaction between flying body and flows transforms the kinetic energy to internal energy, increasing temperature to a very high degree, which leads to ionization of the air and forms a plasma sheath surround the vehicle. Plasma with high density attenuates the radio wave, prohibiting the successful transmission of communication signals between the spacecraft and the ground control, which is known as “blackout” problem. The safety of the aviator is threatened.In this thesis, we calculate the flow field around supersonic RAM-C blunt body at different altitudes. A two-temperature thermal non-equilibrium model is employed. Both 11 species and 7 species chemical models are employed for simulation and compared with each other. The values of pressure, temperature and electron density are obtained. Results are compared with experimental data and shown to coincide. From the simulation results we find our physics model and calculation method is reliable. We also find the characteristics of flow field from our simulation.Numerical study of electromagnetic wave(EM wave) transmission through magnetized plasma sheath is carried out. Plasma parameters in the sheath are extracted from our CFD(computational fluid dynamics) results of flow field in blunt body flight conditions, and serve as input for EM wave calculation. The EM wave we consider is radiated from our designed coaxial feed GPS patch antenna. The external magnetic field is assumed vary linearly in space. Different radiation characters are obtained when changing the applied magnetic field. The study shows that EM wave propagation in non-uniform magnetized plasma is a matter of matching, and the EM wave transmission can be improved only when the applied magnetic field is in a proper value.