明渠流动S-K模型参数率定的随机搜索法

Optimization of parameters in S-K Model for open channel by using random searching technique

S-K模型(Shiono and Knight Method)是目前进行单一和复合断面顺直棱柱体明渠水力计算较为精细的模型之一。涉及3个待定参数:摩阻系数f、无量纲涡粘性系数λ和二次流影响因子Γ,这3个参数的待定性使该模型在实际工程应用中受到限制。本文结合大量的水槽试验流量Q及壁面切应力τb结果,采用随机搜寻法,对S-K模型中的3个重要参数进行了同时满足Q和切应力bτ条件下的优化率定。结果表明,参数f变化规律与Colebrook-White公式基本一致,λ和Γ随渠道宽高比Pb/Pw的变化规律较为明显。

The Shiono-Knight Method is an effective model for hydraulic calculation of prismatic open channel with arbitrary cross section. However, the application of this method is not popular in engineering design since three unknown parameters, namely friction coefficient f, dimensionless vortex viscosity and secondary flow factor Г are involved. In this paper, based on a great amount of experimental data including the discharge and wall shear stress the random searching technique is applied to optimally calibrate these three parameters with both discharge and shear stress conditions of flow conditions can be fullfilled. The result shows that the variation of friction coefficient is in good agreement with the formula given by Colebrook-Ehite, and the other two parameters are significantly change with the ratio of channel width to depth.