出渗对均匀大粒径泥沙附近水动力特性影响

Effect of upward seepage on hydrodynamic characteristics around uniform coarse grains

为探讨出渗对均匀大粒径泥沙颗粒周围水流特性的影响,基于粒子图像测速技术(PIV)对出渗影响下的均匀大粒径泥沙颗粒群周围水流结构进行测量,并对不同出渗强度下颗粒群周围立面二维流场结构进行了分析。试验结果表明:出渗能够减小颗粒群周围原水流运动方向的流速,而增大垂直向上的流速,且两者均随着出渗强度的增强而对流速的影响愈加明显;根据实测数据,拟合出考虑出渗影响下的均匀大粒径泥沙周围纵向流速分布公式,相关性较好;出渗能增强颗粒群附近的紊动强度,加剧周围水体的能量耗散;随着出渗强度的增强,颗粒群周围的涡量值随之减小。

In order to study the influence of upward seepage on the flow characteristics around uniform coarse grains, we experimentally measured the flow structures around uniform coarse grains under the impact of upward seepage by the technique of Particle Image Velocimetry （PIV）, we subsequently analyzed the two-dimensional vertical flow structure around the particle group with different relative upward seepage intensities. The results show that upward seepage decreases the velocity along the mainstream direction and increases the vertical upward velocity around the particle group. With the relative upward seepage intensity increases, both of them become more affected. We also proposed an empirical formula for the longitudinal current velocity distribution under the impact of upward seepage based on the measurements. We finally found that the upward seepage could enhance the turbulence intensity and energy dissipation around the particle group, and the value of vorticity around uniform coarse grains decreases with the increase of relative upward seepage intensity.