横风作用下高铁全封闭矩形声屏障气动性能

Aerodynamic performance of fully enclosed rectangular noise barrier in High-speed railway under crosswinds

我国沿海地区已规划(有部分已建成)多条重要的且穿越居民聚集区的高铁线路,多种型式的全封闭矩形式声屏障将在该区域的高铁沿线上广泛运用。近年来,在西太平洋生成的较大台风频繁在该地区登陆,该地区高铁桥上声屏障结构频繁遭遇强横风侵袭。为给高铁桥上全封闭矩形式声屏障结构的抗风设计提供理论依据,参照缩尺比为1∶16.8的列车-声屏障动模型试验装置,建立相同比例的横风-列车-桥梁-声屏障三维精细化CFD数值仿真模型;采用大涡模拟(LES)方法分析横风作用下2种全封闭矩形式声屏障的气动压力以及流场结构;基于本征正交分解(POD)理论,采用Matlab软件分别对横风作用下2种全封闭矩形式声屏障的绕流流场进行分解,探讨各阶模态对其湍动能的贡献。研究结果表明:1)全封闭矩形式声屏障绕流流场的湍流强度在纵向分布上呈两端小、中间大的规律,内部流场湍流强度高于相应的声屏障外侧,该差异在声屏障中间区段表现最为显著。2)在声屏障进、出口顶部开孔将导致全封闭矩形式声屏障内侧的负压值降低82%,湍流强度升高114%。3)相对于全封闭矩形式声屏障,进、出口开孔式声屏障出现端部绕流现象的纵向区域更长,且相应的湍流模态组成极为复杂,全封闭矩形式声屏障在进、出口顶部开孔将导致横风风致振动加剧。

A number of important high-speed railway lines have been planned(some of them have been built) in coastal areas of China, and various types of fully enclosed rectangular noise barriers will be widely used along the high-speed railway lines in this area. In recent years, large typhoons generated in the western pacific frequently landed in this area, and the noise barrier structure of high-speed railway bridge in this area was frequently attacked by strong crosswinds. In order to provide theoretical basis for wind resistance design of fully enclosed noise barrier structure with moment form on high-speed railway bridge, a 3D fine CFD numerical simulation model of crosswind-train-bridge-noise barrier with the same size was established by referring to the dynamic model test device of train-noise barrier with scale ratio of 1:16.8. The large eddy simulation(LES) method was used to analyze the aerodynamic pressure and flow field structure of two fully enclosed barriers under crosswinds. Based on proper orthogonal decomposition(POD) theory, Matlab was used to decompose the flow field around the noise barrier with two forms under crosswinds. The contribution of each mode to its turbulent kinetic energy was discussed. The results are drawn.(1) The longitudinal distribution of turbulence intensity around the noise barrier with fully enclosed form is small at both ends and large in the middle. The turbulence intensity inside the noise barrier is higher than that outside the noise barrier, and the difference is most significant in the middle of the noise barrier.(2) Opening holes at the top of the inlet and outlet of the noise barrier will reduce the negative pressure inside the fully enclosed noise barrier by 82% and increase the turbulence intensity by 114%.(3) Compared with the fully enclosed barriers, the longitudinal area of the barrier with opening holes in the top of both ends is longer, and the corresponding turbulent modal composition is extremely complex;the fully enclosed barrier with opening holes in the top of both ends will lead to the intensified wind-induced vibration.