非淹没复式断面丁坝区的流速分布规律

复式断面丁坝是常见的航道整治建筑物。通过室内水槽试验开展非淹没复式断面丁坝流速分布规律研究。结果表明①表层合流速高速区主要出现在一级丁坝坝头下游外侧,二级丁坝长度b₂对高速区流速大小及平面分布形态具有明显影响,而弗劳德数Fr只影响高速区流速大小,表层横向流速平面分布接近扇形,最大横流可达试验流速的0.45倍;②横断面上纵向流速高速区位于一级丁坝坝头附近,强横流区位于二级丁坝前缘,均呈带状分布,b₂越大,带宽越小,高速区分布更为集中;③纵剖面上纵向流速最大值出现在丁坝下游靠近水面附近,其沿程位置随b₂的增大而上移,横向流速呈先增大后减小的变化,最大值出现在丁坝附近靠近槽底的部位,强横流区呈枫叶型分布。研究结果可为航道整治工程设计和丁坝水毁保护等提供参考。

Flow Velocity Distribution Around Non-submerged Spur Dike with Compound Section

Spur dike with compound section is a common structure used in waterway regulation.In this paper,the law of velocity distribution around non-submerged spur dike with compound section is researched via flume experi-ment,and the results manifest that:I)In surface layer,large resultant velocity appears outside the downstream of the first-stage spur dike head;the length (b2)of the second-stage spur has noticeable impact on the value and mor-phological distribution of the zone of large resultant velocity whereas Froude number (Fr)only affects the value of velocity;transverse surface velocity distributes in an approximated fan shape,with the maximum value up to 0.45 times of test velocity.(Ⅱ)In cross-sectional scale,large longitudinal velocity is located in the adjacent of the head of the first-stage spur dike,and intense transverse velocity zone is in the front of the second-stage spur dike,both distributing in a band shape;with the increase of b2,the band width declines,and the distribution is more concen-trated.(Ⅲ)In longitudinal profile,the maximum longitudinal velocity is found in the downstream of the spur dike near water surface,and its position moves up along with the increase of b2;while the transverse velocity increases first and then decreases,with its maximum value arising close to the bottom;intense high transverse velocity zone stretches in a maple leaf shape.The research results provide reference for waterway regulation and spur dike protec-tion.