岛屿尾流近区浓度的分布特性

对岛屿尾流近区的污染物混合输移特性进行了研究。采用平面激光诱导荧光 (PL IF)技术 ,在恒定来流中 ,分别对圆柱和正弦形状岛屿后 7倍岛屿半宽度范围内的浓度场进行了测量。分析了长时间平均浓度场、脉动浓度场、最大浓度场和尾流浓度断面半宽度的沿程变化规律和大尺度旋涡的存在对尾流区污染物混合输移的影响。结果显示 ,在同样来流条件及排放浓度下 ,正弦形岛屿近区尾流内积聚的污染物浓度大于圆柱形岛屿近区尾流内的浓度 ;基于平均浓度场和脉动浓度场而得到的尾流浓度半宽度大致相同 ,在实验范围内是线性发展的。本研究不仅是环境水力学学科发展的需要 ,而且有利于水污染的控制

Concentration field in near wakes

The planar laser induced fluorescence (PLIF) technique was employed to study the characteristics of pollutant mixing and transport in wakes behind island type bodies. The concentration fields behind cylinder and sinusoidal shaped islands were measured for steady inlet flow over a distance of seven radii downstream of the body. The mean, root mean square and maximum concentration fields and wake half width were analyzed. The results show that more pollutants accumulated behind the sinusoidal shaped island than behind the circular island for the same inlet flow and pollutant discharge conditions. The wake half widths based on the mean and r.m.s. concentration fields were approximately the same and grow linearly with increasing distance from the islands. The impact of the large scale vortex structure on the pollutant mixing and transport in wakes was also analyzed. This study will be helpful to pollution control behind island type bodies.