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通过水深平均纵向与横向流速的乘积(UV)d和垂线平均流速的平方Ud2获得了二次流项系数K的横向分布;根据(UV)d和Ud2在各区域内的关系,引入常系数a和b来表征二次流,进而给出了新的垂线平均流速二维解析解。该解析解表明,b只出现在水深线性变化区域的解析式中。分析发现,a的符号代表各区域内二次流的旋转方向,二次流强度则由a和b的取值共同决定;各区选定合适的a值可以得到较好的计算结果,b值对流速分布的影响主要在主槽区和主槽边坡区。采用英国FCF不同系列试验资料对计算模型进行验证,结果表明,计算值与实测值吻合较好。同时,比较了a和b在不同断面形态的复式河槽中的取值,并就其变化规律进行了分析。
The horizontal distribution of the coefficient k of the secondary flow entry is obtained from the product of the average vertical and horizontal flow velocity (UV) d of the water depth and the square of the vertical average flow velocity Ud2. Based on the relationship between (UV) d and Ud2 in each region, a and b to characterize the secondary flow, and then give a new two-dimensional analytical solution of the average vertical velocity. The analytical solution shows that b only appears in the analytic formula of the linear range of water depth. The analysis shows that the sign of a represents the rotation direction of the secondary flow in each region, and the strength of the secondary flow is determined by the values of a and b. The appropriate a value in each region can get a better calculation result. The b value The influence of flow velocity distribution is mainly in the main groove area and the main groove slope area. The test data of different FCF series in the UK are used to verify the calculation model. The results show that the calculated values are in good agreement with the measured values. In the meantime, the values of a and b in the multiple channels with different cross sections are compared and their variation rules are analyzed.