The Research And Design Of The Wake Bubbles Imaging System

Wake is motive bubble film with special physical information. It is due to reasons such as propeller cavitation, wave breaking and the air drawn into waterline when ship sail. It is the base for the wakes research to obtain the parameters of wake bubbles, and wake’s optical characteristic can offer a new approach for torpedo guidance and detection. Therefore the research in wake bubbles measurement carry out for a longtime abroad, various bubble imaging systems designed have gained data in experiments. There is a big gap between domestic research and overseas in this field. With the development of the domestic research, a imaging system for wake bubbles measurement is needed urgently.In this paper, a wake bubbles imaging system is presented based on "study of wake bubbles characteristics and parameters measurement". Considering the difficulties in the imaging of wake bubbles, this paper analyses the micro bubbles imagine technology, optical design, mechanical structure design and experiments et, al. It mainly includes the contents as follows:First, the background and significance of this research were introduced, it also presents the domestic and foreign progress of optical technology for wake bubbles measurement, detailedly the high-speed photography.Second, we contrast and analyze several optical measurement methods, and finally choose the high-speed photography as the appropriate means in this system. According to the underwater environment, system design target and the law of bubbles motion, the difficulties of wake bubbles imaging were presented. Thereby, with the combination of wide and narrow FOV imaging systems, technical solution was established. Technologies such as laser sheet were also studied.Third, to avoid the image stacking of bubbles and increase the image contrast, laser sheet is used to illuminate the wake zone in narrow FOV imaging system. Because the particle size of bubbles is in a wide range, three switchable magnification lenses are designed for the bubbles imaging. Lenses are split into front and rear groups, with parallel rays transmit between them. With the sweeping of laser sheet, the image information of bubbles in a volume can be sampled. Moreover, by keeping the front group moving synchronously with laser sheet, bubbles can always image clearly when laser sheet sweeps. After the calculation and the optimal design for optical path, the accurate values for every optical element were established, the aberrations evaluation and tolerance analysis for this optical system were also presented. It’s also discussed that the influence on image quality when laser sheet sweeps, the determination of laser sheet thickness and the system distortion correction. For large FOV imaging system, mature products purchased can meet the design requirements.Fourth, the mechanical structure design for the whole system is presented such as: the seal housing of the large and narrow FOV systems, the switch mechanism of the rear group lens and the synchronous travel mechanism of laser sheet with front group lens in the narrow FOV system, et.al. It is also analyzed that the tightness and the resistance to pressure of the housings.Fifth, the several factors that affect the system accuracy are analyzed and the relevant error is analyzed. Then we introduced the system’s experimental setup and the relevant experimental results were obtained. After, the experimental results were analyzed.