弯道床面切应力的研究

弯道床面切应力是弯道泥沙起动的直接动力,运用弯道水流概化模型试验,利用先进的ADV进行了三维流速数据的采集。弯道水面横比降与纵比降的沿程分布公式以及弯道水流纵向垂线平均流速计算方法,从理论上进一步推导得到了弯道床面切应力分布的公式。通过计算,给出了不同参数对弯道床面切应力分布的影响。研究表明,计算床面切应力的分布不仅与前人研究成果基本一致,而且更加完善和系统化,为深入探讨弯道水流特性奠定了基础。

Bed Shear Stress in Curved Conduit Flow

The bed shear stress in bend flow is the direct motivation for sediment initiation,which is an important issue for hydraulic engineers to concern about.A generalized curved conduit flow experiment is employed to systematically study the flow characteristics and the kinematical law.The 3D flow velocity parameters are measured by adopting the ADV(Acoustic Doppler Velocimeter).Based on the proposed calculation methods of water surface transverse gradient,longitudinal gradient in curved flow and depth averaged longitudinal velocity distribution,a set of formulas to compute the bed shear stress in bend flow are theoretically established.Then each different parameter affecting the bed shear tress is calculated independently and in detail to obtain the distribution pattern of the bed shear stress.Results show that the research achievements are in accordance with the predecessors' findings basically.However,it is relatively more systematical and ideal,which can be taken as the basis to explore the hydraulic characteristics profoundly.