Three-Dimensional Flow Characteristics Of Non-submerged Spur Dike With Two-stage Compound Section

Two-stage compound section of spur dike widely used in channel regulation project,but studies on its flow characteristics lack rarely involved.Based on the flume experiment,numerical simulation and theoretical analysis,and after studying the three-dimensional flow characteristics of non-submerged spur dikes with two-stage compound section,the main results of this study are as follows:（1）Analyzed the length L_d1 and the height H_d1 of one level spur dike,the length L_d2 of two-level spur dike,Froude number Fr and the effect rule of the positions of longitudinal and transversal sections on the distributions of flow profile in vertical and horizontal direction;Discussed the distributing characteristics of the change of free water surface elevation,analyzed single and two-stage of spur dike section under the effect of free surface elevation difference change.（2）Based on the result of numerical simulation,set up the calculation formula of average height of backwater in upstream section of spur dike and verified it with measured data from flume experiment,the results are good;Derived the calculation formula of recirculation length and recirculation width in downstream of spur dike.（3）Expounded the functions L_d1、H_d1、L_d2、Fr impacted surface plane section and dam axis section of cross sections of two-level spur dike on flow velocity in vertical direction;With results of numerical simulation calculation,the calculation formula of stopped flow in dam axis section is established.（4）Based on measured data in flume experiment,explored the influence of Fr、L_d2 on turbulence probability density,absolute turbulence intensity σ_ui,Reynolds stress τ_ij and turbulence kinetic energy E,researched the distributions law of these four turbulence parameters in longitudinal,transversal and vertical direction.