陡坡条件坡面薄层水流沿程变化及水流阻力计算

基于系列陡坡水槽条件不同坡面粗糙程度薄层水流试验,测试分析了坡面薄层水流运动参数沿程变化,并进一步讨论了坡面水流阻力计算方法。结果表明：光滑坡面条件同一流量流速随坡长的增加而增加,而对于较粗床面或较陡坡面流速沿程出现了峰谷变化;由于陡坡条件下坡面薄层水流参数呈现沿程变化的特征,因而传统意义上常用的平均水力参数法计算水流阻力已不适宜于陡坡条件,基于沿程水流阻力计算的方法更加可靠。     

渐变河道水流结构及局部水头损失特性研究

河宽渐变是天然河道的普遍形态特征。运用声学多普勒流速仪（ADV）测量了渐变河道模型的水流结构。试验结果表明：渐变河道形态对水流结构影响明显,在渐缩段和渐扩段产生二次环流,前者影响效应大于后者,且方向相反。基于 SMS 水动力学模型对渐变河道水流特性进行了二维数值模拟,与实测值吻合较好,并计算分析了局部水头损失系数沿程的变化规律。     

坡面柔性植被阻水效应及其局部水头损失特性试验研究

基于系列坡面流试验,研究了柔性植被条件对坡面流水动力特性的影响.结果表明:由于植被阻水及水流混掺效应,不同区域的水流阻力产生机理存在着显著差异,在植被尾部和水跃段区域,局部水头损失系数与单宽流量的关系分别表现二次曲线特征及指数衰减趋势.此外,基于本试验的植被条件排列方式,以染色法测试坡面流表面流速,得出坡面流平均流速的修正系数约为α=0.23±0.02.     

Experimental study of the flow structure of decelerating and accelerating flows under a gradually varying flume

The turbulence characteristics of both decelerating and accelerating flows under a gradually varying flume are investigated by using a three-dimensional down-looking acoustic Doppler velocimeter(ADV). The time-averaged velocity profiles are flatened except for the central parts, and fairly fit into logarithmic laws and those in the plane circulation under the gradual expansion are more likely to be negative. The complex secondary currents are identified under the present gradual transition attributed to the combination of driving forces induced by both the boundary configuration variation and the unbalanced turbulence: a circulation on each side of the expansion and a pair of circulations on each side of the contraction. One sees an anisotropy in the turbulence intensities, the turbulence intensities increase or level out with the flow depth except those under expansion, and the V component of the turbulence intensity typically outweighs that in the streamwise direction. Apart from the above results, the respective particular distributions of the primary Reynolds shear stresses(xy? and xz?) under the gradual expansion and contraction can account for the patterns of the secondary currents in this investigation.     

山区宽窄相间河道平面二维水流数值模拟

针对山区河道受地质条件及河床演化的影响,其平面形态常呈现宽窄相间的渐变形态特征,采用贴体坐标法剖分正交贴体曲线网格求解域,用有限体积法离散控制方程,以SIMPLER计算程式求解耦合方程,建立山区宽窄相间河道平面二维水流数学模型。将模型计算值与宽窄相间水槽水流试验实测值及水动力学SMS软件计算结果进行比较,结果表明:该模型能够较好地模拟宽窄相间河道平面二维水流运动特性,宽窄相间河道河宽渐变将引起水深和流速的变化,在河道最窄处水深降到最低,流速最大;在河道最宽处水深达到峰值,流速最小。