Influence Analysis Of The Roughness Strip On Shock Wave In The Curved Spillway Chute And Study Of Layout Parameters

In view of the research on the roughness,the predecessors have clarified the hydraulic characteristics,energy dissipation and diversion mechanism of the roughness in the bend,but the analysis of the impact of the roughness on the flow shock wave in the bend and the optimal layout parameters of the roughness have not been carried out.In this paper,the relevant tests are carried out to analyze the impact of the roughness on the characteristics of the shock wave and put forward the general layout parameters of the roughness.Frist,by designing a spillway model with a center angle of 60° and a central axis radius of 75 cm,comparing the flow energy and water surface structure of the shock wave in the spillway bend with without the roughness strip,analyzing the influence of the roughness strip on the characteristics of the shock wave in the bend flow,and using the numerical simulation to calculate the model to get the flow field of the water body in the spillway,understanding the interference principle of the roughness strip on the shock wave.Secondly,the flow shock wave can be divided into two aspects:flow energy and water surface structure.Through model test and single factor progressive analysis method,the influence of the change of relative height,arrangement angle and arrangement rate of roughness strips on the flow energy and water surface structure of shock wave is studied.At last,taking the dissipation rate of section water energy,the average cross gradient of water surface and the flow pattern of spillway as the evaluation indexes,the paper compares the improvement effect of relative height,arrangement angle and arrangement rate of roughness strips on the shock wave of spillway,and determines the parameter values of three factors of roughness strips.Through the above research,the results show that:(1)In the research process of the impact of roughness strips on the characteristics of shock wave,the change of shock wave before and after the scheme of arranging roughness strips in the spillway is compared.After the arrangement of roughness strips,the average water depth increases,the average velocity decreases,and the water energy dissipation rate of outlet of bend chute(21#section)is more than 40%,which shows that roughness strips reduce the energy of water shock wave and share part of water for energy dissipation buildings flow energy.The uniformity of water depth after the layout of the roughness strip is higher than that under the scheme without the roughness strip,and the linear distance required to recover to the uniformity of 0.9 is shorter than that under the scheme without the roughness strip,which shows that the roughness strip not only adjusts the water surface structure of the shock wave,but also reduces the work quantity of the spillway.Through the numerical simulation of the flow field,it can be seen that the roughness strip interferes with the shock wave by the reaction force,and the bottom water flow is forced by the roughness strip from the concave bank to the convex bank,which improves the shock wave potency.(2)In the research process of the arrangement of the roughness factors affecting the shock wave,the range of the change of the water energy dissipation rate caused by the change of the relative height,the arrangement angle and the arrangement rate of the roughness strip under the condition of the height of 1 cm is 20.8 At 18.38,31.68,and 1.5cm height,the corresponding range is 14.9,13.42,and 34.97.Therefore,the order of significance of roughness factors affecting shock wave energy is arrangement rate,relative height,and arrangement angle.For the shock wave water surface structure,the range of the average water surface cross slope reduction rate corresponding to the change of the relative height,arrangement angle and arrangement rate of the roughness strip at the height of 1cm is 10.78,14.25 and 17.87,and the range corresponding to the height of the roughness strip at the height of 1.5cm is 12.19,16.70 and 31.09.It can be seen that the significant order of the roughness factors affecting the adjustment of the shock wave water surface structure is arrangement rate,arrangement angle and phase For the height,(3)In the research process of the layout parameters of the roughness strip,the layout method of the roughness strip is determined by the water energy dissipation rate of the cross section,the average cross gradient of the water surface,the flow pattern of the spillway and other indicators.Through comparison and selection,the relative height of the roughness strip is 0.4H(water depth of section before entering the bend),the layout angle is 30°,and the layout rate is 25%,which is the best layout method of the roughness strip.