中文摘要：

该文介绍了在实验段为1．7m×0．4m×0．4m的小型风浪槽中进行的自由表面附近，小攻角翼型流场分离特性的PIV实验结果。实验测量了NACA0012翼型在10°攻角下与自由表面多种不同间距时，翼面附近速度场，而后将各间距下连续采集的约500副瞬态流场结果进行统计分析，获得了翼面时均速度场等信息，讨论了时均流场结构和速度分布随翼型与水面间距的变化规律及水面对翼面流场分离特性的影响。实验的雷诺数Re=5．7×10^4。实验结果表明，随着翼型与自由表面间距的不同，翼型表面流动结构和气流在翼型表面的分离结构发生明显的变化，其明显的变化特征为，随着翼型从无水面干扰的工况向水面接近的过程中，上表面的分离先逐渐增强，而后被抑制，该流动演化特性进而可引起作用于翼型的气动特性的变化。

英文摘要：

PIV experimental results of wake flow structure of a NACA0012 airfoil with small angle of attack mounted above water surface are presented in this paper. The experiment was carried out in a small-scale wind-wave tunnel. The size of wind-wave tunnel is 1.7m（long） ×0.4m （width） ×0.4m （height）. The flow fields around the airfoil were measured at four different conditions with varying the distance between the airfoil and the water surface. The angle of attack of the airfoil keeps 10° during the experiment. For each experimental condition, the time series of particle images were captured to calculate the continuous evolution of the velocity fields and the velocity fields were ensemble averaged to get the statistic parameters, such as mean velocity. The results indicate that the flow structures and the separation character near the airfoil vary remarkably with the changing of the distance between the airfoil and free surface.