鼻坎型式对挑流局部冲刷影响的数值模拟

Numerical Simulation of the Effects of Flip Bucket Pattern on Local Scour of Pick Flow

挑流消能为高水头水利枢纽主要泄洪方式,耗散能量的同时会对下游产生剧烈冲刷。为分析冲刷坑形成原因,探究鼻坎型式对于冲刷的影响,针对某一具体工程,采用自编程序以临界起动切应力作为泥沙起动条件进行数值模拟,结果表明:差动式鼻坎挑流水舌集中,单宽流量大,冲刷深度深,河床冲刷严重;舌型鼻坎挑流水舌横向扩散较大,单宽流量小,冲刷深度较浅。将计算结果与物理模型试验结果对照,两者基本吻合。证明通过用户自定义编程方法进行数值模拟能够较为准确的预测冲刷坑范围与深度,合理的鼻坎型式对于削弱下游冲刷效果显著。

As the main flood discharge method of high head water conservancy project,the pick flow will dissipate energy and cause severe scour to the downstream.In order to analyze the formation reasons of scour pits and explore the influence of flip bucket pattern on scour,for a specific project,a self-programmed numerical simulation was carried out with the critical starting shear stress as the starting condition of sediment.The results show that the differential nose scuttle flow tongue is concentrated,the single width flow is large,the scour depth is deep,and the river bed has been soured seriously.Tongue type nasal ridge flow tongue transverse diffusion is larger,single width flow is small,wash depth is shallow.The calculated results are in good agreement with the physical model test results.It is proved that the range and depth of scour pit can be predicted accurately by using the user-defined programming method,and the reasonable type of nose scuttle can significantly reduce the downstream scour.