Research on jet velocity measurement technology based on firelight radiation

DOI:	10.11809/bqzbgcxb2024.04.016
Keywords:	velocity measurements; concentrating jets; optical attenuation; correlation analysis; passive velocity measurement
Abstract:	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 6 500 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.
Published:	2024-04-30
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