空间滤波测速法具有结构简单、稳定性好和适用性强等优点, 但传统线阵CCD空间滤波测速法要求CCD阵列方向与待测物体的运动方向一致, 因此不适合测量复杂的流场。针对这一问题, 本文提出了基于面阵CCD相机的空间滤波测速方法。对采集到测量区域的一系列面阵CCD输出图像进行处理, 在图像水平方向和垂直方向分别进行隔行采样, 模拟多狭缝空间滤波特性, 实现了对障碍流颗粒速度的光学非接触式测量。针对复杂流场功率谱密度的特点, 利用能量重心校正频谱提高了系统测量精度。通过调节传送带速度对本系统进行标定, 实现了不同速度下的流速测量, 平均误差小于4%。利用本系统还测量了由玻璃砂模拟的泥石流速度场分布, 最后讨论了空间周期和测量时间对测量结果的影响。结果表明, 采样时间大于0.5 s时, 测量结果趋于稳定, 空间分辨率最小可达1.28 mm。

The spatial-filtering velocimetry method has the advantages of having a simple structure, good stability, and strong applicability. However, the traditional linear-array Charged Coupled Device (CCD) spatial-filtering velocity measurement method requires that the direction of the CCD array be the same as the direction of motion of the object whose velocity is to be measured . Therefore, this method is not suitable for measuring complex flow fields. To solve this problem, this study proposes a spatial-filtering velocity- measurement method based on an area-array CCD camera. A series of area-array CCD output images were collected from the measurement area. Interlaced sampling was performed in the horizontal and vertical directions of the image to simulate the multi-slit spatial-filtering characteristics, and an optical non-contact measurement of flow particle velocity around an obstacle was realized. Moreover, regarding the characteristics of the power spectrum density of complex flow fields, using an energy center-of-gravity correction spectrum improves system measurement accuracy. The system was calibrated by adjusting the speed of the conveyor to achieve measurements at different speeds with an average error of less than 4%. In addition, the debris-flow velocity-field distribution simulated with glass sand was also measured using this system. Finally, the influence of spatial period and duration on the measurement results was discussed, which demonstrate that the measured velocity reaches a plateau for sampling over 0.5 s and the spatial resolution is improved to be 1.28 mm.