Research On The Measurement System Of Smoke Plume Transmittance

Solid propellant is the power of solid engine rocket. Different plume characteristics are produced by different propellant formulations. If smoke plume concentration is high, it interferes guidance signal and affects guidance accuracy of missile. The Measurement of smoke plume transmittance is the major way to measure the light obscuring power.It is also a main basis to judge the merits and demerits of propellant formulations. The measurement of plume transmittance based on image processing can detect the light obscuring power comprehensively. It avoids many problems. For example, optical sensors are placed wrongly. However, in real practical application, the measurement based on video image was easily affected by environment, which influences the calculation accuracy. At the same time, incorrect use of background target also affects the precision of measurement. Therefore, it is necessary that it is researched to carry out the related research and establish a practical secondary measurement system of smoke plume transmittance.The paper designs and implements a measurement system of smoke plume transmittance based on visible video, infrared video and laser video images. Based on the analysis of the system requirements, the system design and detail design is achieved. Each module is implemented, which includes the data acquisition module, the calibration module, the calculation module of smoke plume transmittance, the area selection module of target and the configuration module. The wide non-isothermal gray target is used in the paper,which solves the problem that the grey level of target black area on visible image does not change early and exists the narrow dynamic range. The technology also solves the problem that the camera cannot capture the complete image of smoke plume because of narrow target. The multi-background calibration technology is adopted, which increases the collection times of background calibration video. The technology avoids that the calibration curve becomes nonlinear, because of the variation abrupt of luminance. A search algorithm for smoke key frames in video is used, which can locate quickly effective smoke frames and reduce the calculation of smoke transmittance.The system has gone into the actual testing phase.The results turn out that the relative standard deviation of the test results on the smoke plume transmittance of the same propellant is within 8%.The system meets the design requirement.Because that the calibration video acquisition process is easily disturbed by environment, the multi-background calibration technology has decreased the environment effect for the measurement results. However, in complex environments, the calculation precision of the calibration curve and smoke plume transmittance is affected by environment. So the future research should focus more on how to reduce the influence of environment to the measurement tests.