基于火光辐射的射流速度测试技术研究

Research on jet velocity measurement technology based on firelight radiation

为了满足超高速聚能射流的测速要求,采用狭缝光阑与高速光电探测器构成被动探测模块,探测射流的自身火光辐射。测速系统以多级光阑前后排列的方式限制探测幕面的视场与厚度。分别对两级、三级光阑2种滤光模式建立了光学模型,模拟射流过靶时各级光阑的滤光性能。仿真结果表明,三级光阑可以有效衰减射流自身的强辐射,并且可以滤除探测幕范围之外的爆炸火光以及设备内的反射光,滤光效果超过99.25%。采用三级光阑逐级滤光的方法,解决了射流辐射亮度强并且伴随有杂散光导致其速度不易测试的难题。最后在外场进行射流测速试验,得到的信号波形印证了仿真结果的正确性。对过靶信号进行相关性分析处理得到射流的精确过靶时间,计算得到的射流速度为6500 m/s左右。将测得数据结果与高速摄影测速结果进行对比验证,测速系统的不确定度低于1.9%,验证了系统的可行性。

In order to meet the speed measurement requirements of ultra-high-speed shaped charge jet,a slit diaphragm and a high-speed photodetector are used to form a passive detection module to detect the jet’s own fire radiation.The speed measurement system restricts the field of view and thickness of the detection screen by arranging multi-stage diaphragms.In this paper,the optical models of two-stage and three-stage diaphragms light filtering modes are established respectively to simulate the light reduction performance of each stage of the diaphragm when the jet passes through.Simulation results show that the three-stage diaphragms can effectively attenuate the strong radiation of the jet itself,and can filter out the explosion fire outside the detector screen range as well as the reflected light in the equipment,with a filtering effect of more than 99.25%.The method of gradual filtration of three-stage diaphragms has solved the problem that jet radiation brightness is strong and its speed is difficult to test due to the explosion fire.Finally,the jet velocity measurement experiment is carried out in the outfield,and the obtained signal waveform confirms the correctness of the simulation results.The correlation analysis of the over-target signal is processed to obtain the accurate over-target time of the jet,and the calculated jet velocity is about 6500 m/s.The measured data results are compared with the results of high-speed photography.The uncertainty of the speed measurement system is less than 1.9%,which verifies the feasibility of the system.