多波长数字粒子图像测速技术研究

数字粒子图像测速(DPIV)研究中,应用最为广泛的缩短两幅粒子图像之间时间间隔的方法是跨帧技术,这一技术的发展会受到高速相机技术的限制。本文提出了一种新的缩短两幅粒子图像之间时间间隔的多波长激光脉冲照明与多光谱成像技术,利用多个不同波长的脉冲激光照明流场中的同一区域,由多波长成像系统采集不同波长照明下的流场中的粒子图像,不同波长的粒子图像之间的时间间隔只与光脉冲之间的时间间隔有关,不再受相机帧转移时间的限制。根据这一原理设计并搭建了一套双光谱数字粒子图像测速系统,将不同时刻粒子图像之间的时间间隔缩短至50ns。

Research of multi-wavelength digital particle image velocimetry

In a digital particle image velocimetry(DPIV) system,the superior limit of measurable velocimetry depends on the time interval between two particle images.To measure a high velocity,the time interval should be as sort as possible.Frame straddling technology,which highly depends on professional high speed camera,is widely used in DPIV system to reduce the time interval between two particle images.But,by using frame stradding,the time interval must be larger than frame pitch.We describe in this paper a new method,which based on multi-wavelength pulse laser beam illumination and multispectral imaging,to reduce the time interval instead of frame straddling.Using this method,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.A double-wavelength DPIV system is built,and the time interval between two particle images can be reduced to 50 nanoseconds.