高超声速钝锥等离子体鞘套电波传播特性研究

目的改进现阶段地面指控站对临近空间高超声速飞行器的通信和测控效果。方法采用计算流体动力学技术模拟钝锥体在不同高超声速飞行条件下的头身部绕流流场特性,并运用相关公式建立钝锥等离子体鞘套电磁模型。然后运用改进的移位算子时域有限差分方法计算电磁波经过等离子体鞘套的传播特性。结果计算结果表明,电磁波在等离子体鞘套内的传播特性在频率处于最大等离子体频率附近时发生转折,电磁波通过等离子体鞘套的透射效果与飞行工况和入射波条件密切相关。相对其他入射角度,当电磁波垂直于飞行体物面入射到等离子体鞘套尾部时的电磁波衰减较小。飞行高度增加或飞行速度减小时,等离子体鞘套对电磁波的衰减效应将减弱。结论该研究可为有效测控临近空间高超声速飞行器、缓解再入通讯中断现象提供一定的技术突破方法。

EM Wave Propagation Characteristics in Plasma Sheath of Hypersonic Reentry Blunted Cone Body

Objective To improve the communication and monitoring from the ground station to the vehicle. Methods The hypersonic flow field over the blunted cone under different flight conditions in near space was simulated thoroughly by the technology of computational fluid dynamics (CFD). Then the electromagnetic (EM) model of plasma sheath for the blunted cone was set up by making the conversion computation for the flow results through some related formulae. Finally, the propagation characteristics of EM waves interacting with plasma sheath were explored in-depth by using an improved shift-operator finite difference time-domain (SO-FDTD) method. The memory-minimized algorithm is applied to the method to save system memory and improve the calculation speed. The high efficiency and accuracy of the SO-FDTD method proposed in this paper were validated by comparing to analytical method and the SO-FDTD method proposed in the recent reference. Results The calculated results showed that the propagation characteristics of EM waves interacting with plasma sheath were closely correlated with the flight condition and the EM wave incidence state. It was shown that the propagation characteristics of EM wave in plasma sheath presented a turning change around the corresponding maximum plasma frequency. Compared to other incidence angles, the attenuation coefficient of EM wave through the tail region was weaker when the wave was perpendicular to the body surface. As the flight altitude increased or the flight speed decreased, the attenuation of EM wave propagation in plasma sheath can be reduced efficiently. Conclusion The conclusions obtained from this paper can provide the technical breakthroughs for the identification and monitoring of hypersonic near space vehicles and for the remission of the interruption of reentry communication.