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    大型调水明渠中圆柱桥墩的体型优化及消涡减阻效应研究

    Research on Shape Optimization and Eddy Reduction Effect of the Cylindrical Pier in Large-Scale Water Diversion Open Channel

    • 摘要: 在长距离调水渠道上通常修建有大量跨渠桥梁,密集的桥墩绕流阻力叠加必然增加水流能量损失.为了提升调水工程的输水能力,开展渠道桥墩绕流特性与减阻措施的研究十分必要.以大型输水渠道跨渠圆柱桥墩为研究对象,采用理论分析与水动力数值模拟相结合的方法开展了桥墩水动力特性研究.通过分析圆柱绕流特征,确定了尾涡主区分界及形态曲线函数;兼顾湍动能耗散效应与工程应用,提出了头部尖圆、尾部为流线型尾翼的鱼形桥墩新体型.选择流速、压强、湍动能及涡旋强度因子,利用三维水流模拟成果分析了圆柱桥墩和鱼形桥墩的绕流特性及差异,揭示了后者的减阻机理.研究结果表明,鱼形墩具有消涡抑紊作用;与圆柱墩相比,湍动能耗散消减55%以上,涡量衰减53.3%~84.8%,减阻效率不低于30%;在大型渠道试验应用时,鱼形墩水头损失降低48.4%~64.5%,验证了跨渠桥墩新体型的科学性、实用性和消涡减阻效应.

       

      Abstract: Amounts of cross-channel bridges have been built in long-distance large diversion channels,and the accumulation of the flow resistance caused by the numerous piers will inevitably increase the flow energy loss.In order to increase the water transfer capacity of the water transfer project,it is necessary to investigate the flow characteristics around the channel piers and the drag reduction measurements.Taking the cylindrical pier across a large water conveyance channel as the research object,the hydrodynamic characteristics of the pier are researched on basis of theoretical analysis and hydrodynamic numerical simulation.By analyzing the characteristics of cylinder flow,the boundary of the main region of the wake vortex and the shape curve function are obtained.Considering the effect of turbulent energy dissipation and the engineering application,a new shape type of fish-shaped pier with a sharp head and a streamlined tail is proposed.By adopting the factors of velocity,pressure,turbulent kinetic energy and vortex intensity,the flow characteristics of the cylindrical pier and the fish-shaped pier and their differences are analyzed based on 3D flow simulation data,and the drag reduction mechanism of the fish-shaped pier is indicated.The research shows that the fish-shaped pier contributes to vortex elimination and turbulence suppression.Comparing with the cylindrical pier,the turbulent energy dissipation is reduced by over 55%,the vorticity attenuation is up to 53.3%~84.8%,and the drag reduction effect is more than 30%.In the test application used in large-scale channel,the head loss of the fish-shaped pier was reduced by 64%,which verified the scientific and practical as well as the effect of vortex dissipation and drag reduction properties of the new shape type of the cross-channel pier.

       

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