高超声速球模型及流场光辐射和电磁散射特性测量.

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. [ABSTRACT FROM AUTHOR]