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该文采用180°U形矩形截面弯道玻璃水槽模拟天然弯道河流,运用声学多普勒流速仪(acoustic doppler velocimeter,ADV)研究刚性非浸没式植被(密度4.47%)对弯道水流纵向流速分布,横向环流及湍流动能(turbulence kinetic energy,TKE)的影响。实验结果表明,当水槽流量较小时,植被对水流的阻碍作用较小,由流速降低而导致的水深增加现象不明显,当水槽流量增大时候,植被对水位的抬升现象明显;水流受植被“阻滞”作用,弯道处纵向流速沿水深分布不再服从“对数型”分布规律,且原本水流受弯道作用后呈现的“上减下增”效果也消失;植被加快了最大流速区向凸岸转移,到达弯道出口时,最大流速区逐渐转移至断面中部区域;在植被的影响下,各断面弯道环流消失;植被会加剧水流紊动效应,导致湍动加剧,TKE增大。上述实验结论将增进研究者对植被对弯道水流特性影响的理解,同时也为泥沙疏浚,河道生态系统恢复提供指导。
In this paper, a 180 ° U-shaped rectangular curved glass sink was used to simulate the natural curved river. The effect of rigid non-immersed vegetation (density 4.47%) on the longitudinal flow velocity of the curve was studied by acoustic doppler velocimeter (ADV) Distribution, lateral circulation and turbulence kinetic energy (TKE). The experimental results show that when the flow of the sink is small, the vegetation has little impediment to the flow of water, and the increase of the water depth caused by the decrease of the flow velocity is not obvious. When the flow of the sink increases, the vegetation is obviously uplifted by the water level; “Block” effect, the longitudinal flow velocity at the bend no longer obeys the distribution pattern of “logarithmic” along the water depth, and the original effect of “increasing and decreasing decreasing” Vegetation accelerated the transfer of the maximum velocity to the embankment, and at the exit of the curve, the maximum velocity gradually shifted to the middle of the cross-section. Under the influence of vegetation, the circulation of curves at each cross-section disappeared. Vegetation would aggravate the turbulence of the flow, leading to turbulence Increased action, TKE increased. The above conclusion of the experiment will enhance the researchers’ understanding of the impact of vegetation on the flow characteristics of the bend and at the same time provide guidance for sediment dredging and river ecosystem restoration.