高超声速球模型及流场光辐射和电磁散射特性测量

摘要

为了研究高超声速目标及其流场对目标探测和识别的影响,在弹道靶设备上开展了球模型光辐射和电磁散射特性测量.由二级轻气炮发射模型,模型为φ15 mm的球,材料为Al2O3,速度范围4.2～6.1 km/s,靶室压力范围2.0～15.4 kPa,光电倍增管探测器分别测量中心波长为254 nm、365 nm、430 nm的紫外辐射强度和可见光辐射强度,红外InSb探测器分别测量波长为3～5 μm、8～12 μm的红外辐射强度,X波段单站雷达系统测量在视角为40°的全目标雷达散射截面积(RCS).实验结果表明:在给定的实验条件下,模型及流场的光辐射强度和电磁散射特性强烈依赖于模型飞行速度和实验压力;模型及流场紫外辐射、可见光辐射主要为头部激波帽辐射,尾迹基本没有紫外辐射、可见光辐射;模型及流场红外辐射主要集中在模型头部区域,尾迹在3～5 μm波段红外辐射明显且持续时间较长,尾迹在8～12 μm波段辐射不明显;在模型飞行速度较低时,模型及流场的电磁散射能量主要集中在有绕流的模型区域;当模型飞行速度较高时,模型及流场电磁散射能量分布在有绕流的模型区域和尾迹区域;在一定的实验条件下,模型尾迹总目标RCS比等离子鞘套包覆的模型目标RCS大约1个数量级.%The ray radiation and electromagnetic scattering of the sphere models in the ballistic range are measured to investigate the effects of hypervelocity vehicle and flow field on the target detection and recognition.The models are launched from a two-stage light gas gun.The models are the spheres with the diameter of 15 mm,which are made of Al2O3.The velocity ranges from 4.2 km/s to 6.1 km/s,and the target chamber pressure ranges from 2.0 kPa to 15.4 kPa.The intensities of ultraviolet radiation (254 nm and 365 nm) and visible radiation (430 nm) of the models are measured by the photomultiplier detectors,respectively.The intensities of infrared radiation (3-5 μm and 8-12 μm) of the models are measured by using InSb detectors.The radar cross section (RCS) of the full targets is measured by the monostatic radar system working at X waveband,of which the visual angle between the main beam and the flight direction is 40°.The results show that the ray radiation intensities of the models and flow field and the electromagnetic scattering characteristics depend on the flight speeds of the models and the chamber pressure.The ultraviolet radiation intensity is the same as their visible light radiation intensity.The difference of radiation intensity between 3-5 μm and 8-12 μm is within one order of magnitude.The ultraviolet radiation and visible radiation mainly come from the shock wave radiation,which do not present in the wake radiation at all.The intensity of infrared radiation of the wake in the range of 3-5 μm is higher and its duration is longer compared to that of 8-12 μm.The electromagnetic scattering energy mainly comes from the regions of the models surrounded by the flow field when the flight speed is lower,and the electromagnetic scattering energy of the wake is markedly strengthened when the flight speed is higher.The electromagnetic scattering energy mainly comes from the regions of the models surrounded by flow fields and wakes when the flight speed is high.The total RCS of wake is about one order of magnitude larger than that of the model surrounded by flow fields under certain conditions.