为了提高单帧长曝光图像法的颗粒速度测量的测速上限, 以背光成像的单帧长曝光法测速装置为研究对象, 从轨迹识别的角度, 对该方法测速上限的影响因素进行了理论分析和实验研究。结果表明：在背光成像方式下, 颗粒速度越高, 轨迹灰度值越高, 越难以识别; 从轨迹可识别性的角度可知, 影响因素主要包括颗粒直径、颗粒透射率和光源光强; 当光源光强足够时, 背光成像的单帧长曝光法测速装置对直径50 μm不透光圆盘颗粒的测速上限为1250 m/s。

In order to improve the upper limit of particle velocity measurement for single-frame long-exposure imaging method, influence factors of upper limit for velocity measurement are theoretically analyzed and experimentally researched with backlit imaging single-frame long exposure method from the perspective of image grayscale. The results show that for backward illumination, higher particle velocity leads to higher gray value of particle image and more difficult to distinguish it. From the perspective of track recognition, the influencing factors mainly include the particle diameter, the particle transmittance and the intensity of light source. It is found that the upper limit of velocity measurement for the opaque disk particle with the diameter of 50 μm reaches 1250 m/s by using the backlit imaging single-frame long exposure method velocity measurement device when the intensity of the light source is high enough.