明渠柱体上游马蹄涡的运动学特征研究

发布时间：2018-04-27 02:21

本文选题：柱体绕流 + 马蹄涡　；参考：《水利学报》2016年02期

【摘要】：马蹄涡是水下柱体结构周围床面冲刷的主要动力。为掌握马蹄涡的运动学特征,引入了基于旋转强度的马蹄涡识别方法,提出了基于椭圆涡拟合的马蹄涡特征提取方法,其中,椭圆涡由Oseen涡和倾斜单向剪切流叠加而成。基于上述方法,通过开展明渠圆柱绕流PIV实验,对柱体上游对称面时均流场中马蹄涡的运动学特征进行了研究。结果表明,在柱体雷诺数大于104的紊流柱体绕流中,马蹄涡上游的流动分离点随柱体雷诺数的增大而缓慢向下游移动,但马蹄涡的位置保持不变,涡中心距柱体中轴约0.67D(D为柱体直径或宽度),距床面约0.06D;随着柱体雷诺数的增大,马蹄涡的半径不变而强度增加,使得马蹄涡作用于床面的剪切应力增大。研究结果建立了客观提取马蹄涡运动学特征的数学方法,得到了流动分离点、马蹄涡位置等运动学特征随水流条件的变化规律,揭示了明渠柱体绕流与其它流动中柱体绕流的差异,初步构建了马蹄涡的动力作用概念模型。
[Abstract]:The horseshoe vortex is the main force of the bed scouring around the underwater cylindrical structure. In order to grasp the kinematic characteristics of horseshoe vortices, a method of horseshoe vortex recognition based on rotation strength is introduced. A method of extracting horseshoe vortices based on elliptical vortex fitting is proposed. The elliptic vortices are superposed by Oseen vortices and inclined unidirectional shear flows. Based on the above method, the kinematic characteristics of horseshoe vortices in the equinox flow field in the upstream symmetric plane of the cylinder are studied by the PIV experiment of the open channel cylinder. The results show that the flow separation point in the upper reaches of the horseshoe vortex moves slowly downstream with the increase of the Reynolds number of the cylinder, but the position of the horseshoe vortex remains unchanged in the turbulent cylinder with Reynolds number greater than 104. The central axis of the vortex is about the diameter or width of the cylinder and about 0.06D from the bed surface. With the increase of the Reynolds number of the cylinder, the radius of the horseshoe vortex increases and the strength of the horseshoe vortex increases, which makes the shear stress of the horseshoe vortex acting on the bed surface increase. The results show that the mathematical method of extracting the kinematic characteristics of horseshoe vortex objectively is established, and the variation law of kinematics characteristics with water flow condition is obtained, such as the flow separation point, the position of horseshoe vortex and so on. The difference between the flow around the cylinder and the flow around the cylinder in the open channel is revealed, and the conceptual model of the dynamic action of the horseshoe vortex is constructed preliminarily.
【作者单位】：北京交通大学土木建筑工程学院;
【基金】：中国博士后科学基金项目(2015M570031) 国家自然科学基金项目(51078021)
【分类号】：TV133

【相似文献】