本文選題：明渠收縮段 + 室內(nèi)試驗(yàn)��； 參考：《水科學(xué)進(jìn)展》2017年03期

【摘要】：受地形、地質(zhì)等條件影響,明渠收縮過(guò)渡段在輸水工程中十分常見(jiàn),過(guò)渡段長(zhǎng)度過(guò)短,會(huì)導(dǎo)致水面波動(dòng),水體紊動(dòng)加劇。為研究明渠不同長(zhǎng)度過(guò)渡段內(nèi)縱向時(shí)均流速及紊動(dòng)強(qiáng)度的分布規(guī)律,通過(guò)室內(nèi)模型試驗(yàn),利用二維電磁流速儀ACM2-RS測(cè)量了渠道內(nèi)沿程中垂線不同深度處瞬時(shí)流速。試驗(yàn)結(jié)果表明:收縮段內(nèi),縱向時(shí)均流速沿程增加,紊動(dòng)強(qiáng)度沿程降低,遵循渦旋的拉伸機(jī)制和線性扭曲理論;受二次流影響,最大流速位于水面以下,且最大流速的位置隨二次流作用的增強(qiáng)而降低;不同長(zhǎng)度過(guò)渡段對(duì)下游縱向流速分布和紊動(dòng)強(qiáng)度影響不同,過(guò)渡段越短,下游水流紊動(dòng)越強(qiáng),但非渠底附近紊動(dòng)強(qiáng)度沿垂向先減后增的規(guī)律不變。
[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.
【作者單位】： 清華大學(xué)水沙科學(xué)與水利水電工程國(guó)家重點(diǎn)實(shí)驗(yàn)室;西南科技大學(xué)環(huán)境與資源學(xué)院;
【基金】：“十二五”國(guó)家科技支撐計(jì)劃資助項(xiàng)目(2015BAB07B09) 國(guó)家自然科學(xué)基金資助項(xiàng)目(51579130)~~
【分類號(hào)】：TV133
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本文編號(hào)：1734886