Abstract
The hypersonic flow field around a reentry vehicle has a significant influence on the ground-vehicle communication as well as on the detection and recognition of the reentry vehicle. Backward scattering characteristics of a reentry vehicle enveloped by a hypersonic flow field are analyzed using a high-order auxiliary differential equation finite difference time-domain (ADE-FDTD) method in this paper. Flow field parameters, including electron density, neutral particle density, and temperature, are obtained by solving the Navier-Stokes (NS) equations numerically. According to the flow field parameters, distributions of the plasma frequency and the collision frequency are then derived. Based on a validity of the physical model and the high-order ADE-FDTD method, backward radar cross sections (RCSs) of a perfect electrical conductor (PEC) sphere enveloped by a hypersonic flow field under different Mach numbers, heights, and incident angles of the electromagnetic (EM) wave are then investigated. Numerical results show that the incident angle of the EM wave exerts noticeable effects on the backward RCS, which is due to an inhomogeneous distribution of the plasma. The flight height and Mach number have significant influences on the distribution of the plasma that they play an important role in the variation of the RCSs. The results presented in this paper provide useful reference data for practical tests in ballistic range or in the high-frequency plasma wind tunnels, where a sphere target is usually used due to its simple shape.
Highlights
The development of hypersonic reentry vehicles in the near space, such as shuttles, rockets, and missiles, attracts increasing attention in recent years due to their significant strategic position
Most of the efforts were devoted to the analysis of transmission, reflection, and attenuation of EM waves in the plasma sheath in order to alleviate the interruption of plasma on ground-vehicle communication and to find out an alternative approach to bridge the linkage during the blackout time [14,15,16,17]
Numerical simulations are implemented to analyze the features of a hypersonic flow field under different flight conditions and its EM scattering properties when illuminated by a plane wave with different incident angles
Summary
The development of hypersonic reentry vehicles in the near space, such as shuttles, rockets, and missiles, attracts increasing attention in recent years due to their significant strategic position. The plasma flow, which consists of numerous free electrons, ions, and neutral particles, is nonmagnetic, lowtemperature, weakly ionized, and quasi-neutral (i.e., electricity neutral on macroscopic-length scales) [2, 3]. It greatly affects the transmission of electromagnetic (EM) waves that it has a very strong interference on the communication between the reentry aircraft and the ground station; it even leads to blackout in certain conditions [4, 5]. Limited attention was paid to the analysis of the scattering properties of the vehicle enveloped by a hypersonic plasma flow, which plays an essential role in the detection, tracking, and identification of hypersonic targets
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