中文摘要：

为了研究明渠水流流速的时空相关性,在水槽中进行了3种不同比降的恒定均匀流试验。利用粒子图像测速系统（PIV）对水流的时间序列二维流场进行了测量,根据测量结果,分析了流速的时空相关性及其随比降的变化。结果表明：纵向流速空间相关等值线基本呈椭圆形分布,垂向流速空间相关等值线基本呈圆形分布,两者的时间相关曲线均呈一衰减曲线分布;随着比降的增大,同一数值的等值线包含的空间范围减小,而同一时间间隔对应的时间相关系数减小。

英文摘要：

The space-time correlations characteristics of velocity in open channel flows was studied experimentally using steady uniform flow for three slope conditions in an open channel flume. The temporal series of the two dimensional velocity fields were measured by a particle image velocimetry （PIV） system. The characteristics of the space-time correlations and their variations with slope were analyzed based on the velocity data. The results show that the contour of longitudinal velocity spatial correlation is elliptical while the contour of the vertical velocity is circular with both being attenuated over time. The spatial area of each contour and the temporal correlation of each time interval decreases with increasing slope.