以公切角表征的非均匀沙起动流速

Generative flow velocity to non\|uniform sediment expressed by the common tangential angle

引入表征床沙位置的泥沙切点公切线与水平面的交角为参数 ,依据泥沙起动研究床面表层泥沙由静止到运动的临界条件的观点 ,确定了以公切角变化范围表征的泥沙起动判别条件。把非均匀沙的荫暴作用与其在床面位置和起动粒径相联系 ,以公切角表示起动力臂 ,按照指数流速公式形式 ,根据滚动平衡条件推导、建立了与床面位置相关的非均匀沙起动流速公式。给出了平均情况下相应于不同粒径的公切角计算式。利用 1 3组 ,1 33次实验资料对公式进行了验证 ,证明公式具有较高的精度。

The common tangential angle of bed material,whose common tangential line passes through the tangential point of the sediment particles,is introduced in this paper as a parameter to indicate the position of the particles.Based on the standpoint that the study of sediment incipient focuses on the critical condition that the sediment on riverbed is to become to move,variation of common tangential angle is then necessary to determine a criterion for non\|uniform sediment incipient.The generative force arm are expressed by common tangential angle,and the particles,hiding\|exposing action is related with generative flow velocity.Based on the expression of exponential velocity and position of the particals,expression of generative flow velocity to non\|uniform sediment is formulated.Relation between particle diameters and common tangential angle is also formulated under average level.The incipient velocity formula is verified by 13 groups(133 times) of experiment data.Showing that the formula is quite accurate.