Characterization of Plasma Sheath Distribution and Electromagnetic Transport in Hypersonic Vehicles Under Multieffects Coupling

When a hypersonic vehicle flies at high speed in near space, the distribution of key characteristic parameters of the plasma sheath covering the vehicle shows significant changes due to the influence of high-temperature gas effect and wing turbulence interference, resulting in more complicated electromagnetic (EM) transmission characteristics of the target. To more accurately study the distribution characteristics of the plasma sheath and its EM transmission properties of hypersonic vehicles under the coupling of a chemical reaction and near-wall turbulence. The computational fluid dynamics (CFD) method was used to solve the multicomponent 3-D Navier-Stokes equations with chemical reaction source terms, and the Spalart-Allmaras (S-A) turbulence model was introduced to simulate near-wall flow, numerical simulations were performed for different altitudes and velocities. The focus was on researching the distribution characteristics and evolution laws of electron density, particle mass fractions, and EM transmission in the flow field. The results show that considering the near-wall disturbance makes the peak electron density far away from the wall; the air undergoes a violent dissociation-complexity reaction after the excitation wave, the free electrons mainly originate from the contributions of oxygen and nitrogen, and the difference mainly depends on the degree of decomposition of the nitrogen. Finally, the high electron density decreases the transmission coefficient of the EM wave, increases the reflection coefficient, and increases the degree of the EM wave attenuation, and the turbulent near-wall disturbance makes the thickness of the sheath increase, which further aggravates the EM wave attenuation. This study can deepen the understanding of the EM environment of the hypersonic vehicle, and can also provide a reference for the design of the hypersonic vehicle.