单边突扩浅水回流水流结构研究

试验资料表明,回流段流速及底部切应力横向分布沿流向呈自相似性。根据相似原理,水深平均方程可化为常微分方程,经求解获得了无量纲速度剖面公式。验证表阴,速度剖面公式不仅适用于垂线平均流速剖面,而且也适用于沿水深各流层速度剖面。利用速度剖面公式计算的垂线平均流速场与实测值符合较好。拟合了无量纲切应力剖面公式,探讨了主回流区阻力分布规律。 此外,还分析了影响回流长度的因素,建立了回流长度经验公式。

Analysis of Flow Structure in Single Sudden Expansion

The velocity distribution and the bed shear stress distribution in the downstream of a step is found to be self-preserving along stream. Hence, the depth-average equation is transformed into an ordinary differential equation by similarity considerations. The formulas of dimensionless velocity-profile and dimensionless bed shear stress-profile are obtained. The dimensionless velocity-profile formula fits not only the depth average velocity profile but also velocity profile of each layer along depth. The computed results using the dimensionless velocity-profile formula are in close agreement with experimental data. The resistance characteristics of main and recirculating flow and the length of the recirculating flow arc also studied.