【摘要】 非均匀流的水力特性不同于均匀流,水力特性的变化有可能引起糙率的变化。本文采用数值模拟的方法,运用立面二维数学模型对壅水情况下的明渠非均匀流进行模拟,研究非均匀流情况下水力特性和糙率系数的关系。研究表明:壅水情况下,非均匀流能量损失沿程减小,但糙率系数却是沿程增大的。非均匀流中能量损失及糙率系数之间的这种关系是不同于均匀流的,这是非均匀流不同于均匀流的特点之一。根据数值计算结果,拟合得到了较为实用的壅水情况下明渠非均匀流糙率的计算式。将该式用于水库回水水面线计算得到的结果与采用均匀流糙率的计算结果差别较明显,说明采用非均匀流糙率进行水库回水水面线计算是必要的。更多还原

【Abstract】 The hydraulic characteristic in non-uniform flow is different from that under uniform flow condition,which makes roughness change. In this paper,the vertical 2- D numerical simulation is used to simulate nonuniform flow under backwater condition and the relationship between the hydraulic characteristic and roughness is investigated under non-uniform flow condition. Results show that the energy loss decreases,while the roughness increases along the flow under backwater condition,which is different from that under uniform flow conditions. This is one of the characteristics that distinguish non-uniform flow from uniform flow. Based on the simulation results,an empirical formula for roughness used under non-uniform flow with backwater conditions is proposed. Finally the proposed formula is applied to simulate the backwater curve of a reservoir. Significant differences are found between results by using the non-uniform roughness formula and by adopting the conventionally roughness calculations under uniform flow conditions. This research shows the importance of using the non-uniform roughness formula for non-uniform flow simulations.更多还原