科研之友
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摘要
We describe in this paper a DPIV system based on multispectral imaging. The system consists of three pulsed lasers, a laser pulse combined system, a multispectral camera, a synchronizer and a computer with frame grabber. Wavelengths of three pulsed lasers are 532nm, 650nm and 800nm. The laser pulses are combined together into the same beam path to illumine the flow field. The beam splitting prism in the multispectral camera send the 532nm, 650nm and 800nm laser pulses to three different CCD arrays respectively. The narrowband filters in front of the CCD arrays select specific wavebands for every CCD. The three CCD arrays can work independently. They catch three images of the same area of the flow field for different wavelengths at different moments in one exposure period. The synchronizer, which controls the time sequence between the camera and lasers, has a time precision of 1ns and time step length of 50ns. To measure a flow field, firstly, the synchronizer controls the camera to open shutter, then, it controls three lasers to generate laser pulses at different moments in one exposure time to illumine the flow field. With this system we can get three particle images at three certain moments set by the synchronizer in one exposure period (less than 0.14s). The system has been validated in the lab and the result is also laid out in this paper. In this system, the time interval between different particle images just depends on the pulse interval time of different wavelengths, and it is independent of the frame rate of the camera, which is the most important advantage of this system. With different time intervals, this system can be used to measure flow field with different speed level. And further more, by setting two different time intervals for a single measurement, the system can be also used for high speed flow field with complicated structure measurement. Due to its features, perspective of its appreciation should be wide.
- 出版日期2009
- 单位天津大学
