防撞浮箱对桥墩绕流影响的数值研究

Numerical Study on Influence of Anti-Collision Pontoon on Flow around Bridge Pier

在桥墩自由液面处加装防撞浮箱是目前常用的桥墩防撞方法。为了揭示防撞浮箱对桥墩绕流的影响,该文选取圆形桥墩,通过求解不可压缩流动RANS方程,采用雷诺应力(RSM)湍流模型,数值模拟了加装防撞浮箱的桥墩绕流。首先通过与圆柱绕流模型试验的对比,验证了数值仿真方法的合理性和结果的精确度;然后再进行不同水深下,加装不同截面形状和不同截面尺寸防撞浮箱的桥墩绕流数值计算,分析了防撞浮箱和水深对桥墩阻力系数、流场结构以及桥墩局部冲刷的影响。结果表明:加装防撞浮箱将增大整个结构的阻力,改变桥墩后部的涡结构;防撞浮箱截面形状和尺寸的变化都会对桥墩绕流产生影响,进而影响桥墩自身结构和桥区航道的安全通航,此外水深变化也是不可忽略的因素。研究结果可为桥墩防撞浮箱设计提供相关参考。

It is a common method to install anti-collision pontoon on the free surface of bridge pier.In order to reveal the influence of anti-collision pontoon on the flow around piers,a circular pier is selected and the flow around a pier with anti-collision pontoon is numerically simulated by solving the RANS equation of incompressible flow and adopting the Reynolds stress(RSM)turbulence model.Firstly,the rationality of the numerical simulation method and the accuracy of the results are verified by comparing with the model test of the flow around a cylinder.Then,the numerical calculation of flow around a pier with different cross-section shapes and sizes of anti-collision pontoon in different water depths is carried out.The effects of anti-collision pontoon and water depths on the drag coefficient,flow field structure and local scour of the pier are analyzed.The results show that:The anti-collision pontoon will increase the resistance of the whole structure and change the vortex structure behind the pier,the change of cross-section shape and size of anti-collision pontoon will affect the flow around the pier,and then affect the structure of the pier itself and the safe navigation of the channel in the bridge area,and the change of water depth is also a factor that cannot be ignored.The research results can provide some reference for the design of anti-collision pontoon of bridge pier.