明渠收缩过渡段流速分布及紊动特性试验

发布时间：2018-04-11 06:52

  本文选题：明渠收缩段 + 室内试验　； 参考：《水科学进展》2017年03期

【摘要】：受地形、地质等条件影响,明渠收缩过渡段在输水工程中十分常见,过渡段长度过短,会导致水面波动,水体紊动加剧。为研究明渠不同长度过渡段内纵向时均流速及紊动强度的分布规律,通过室内模型试验,利用二维电磁流速仪ACM2-RS测量了渠道内沿程中垂线不同深度处瞬时流速。试验结果表明:收缩段内,纵向时均流速沿程增加,紊动强度沿程降低,遵循涡旋的拉伸机制和线性扭曲理论;受二次流影响,最大流速位于水面以下,且最大流速的位置随二次流作用的增强而降低;不同长度过渡段对下游纵向流速分布和紊动强度影响不同,过渡段越短,下游水流紊动越强,但非渠底附近紊动强度沿垂向先减后增的规律不变。
[Abstract]:Due to the influence of topography, geology and other conditions, the open channel contraction transition section is very common in water conveyance projects. The short length of the transition section will lead to water surface fluctuation and increase of water turbulence.In order to study the distribution of longitudinal mean velocity and turbulence intensity in different length transition sections of open channel, the instantaneous velocity at different depth along the vertical line in the channel was measured by using two-dimensional electromagnetic velocimeter (ACM2-RS) through laboratory model tests.The experimental results show that the average velocity increases and the turbulent intensity decreases in the contraction section, following the stretching mechanism of vortex and the theory of linear distortion, and the maximum velocity lies below the water surface under the influence of secondary flow.The position of maximum velocity decreases with the increase of secondary flow, and the effect of different length transition on the longitudinal velocity distribution and turbulence intensity is different, the shorter the transition section is, the stronger the turbulence is in downstream flow.However, the turbulent intensity decreases first and then increases along the vertical direction near the non-channel bottom.
【作者单位】： 清华大学水沙科学与水利水电工程国家重点实验室;西南科技大学环境与资源学院;
【基金】：“十二五”国家科技支撑计划资助项目(2015BAB07B09) 国家自然科学基金资助项目(51579130)~~
【分类号】：TV133
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本文编号：1734886