大风区段开孔式挡风墙对正馈线气动特性的影响

Influence of perforated wind-break wall on the aerodynamic characteristics of positive feeder in gale areas

兰新高速铁路常年遭受风灾,挡风墙的修建虽有效防止了列车倾覆,但加剧了接触网正馈线的舞动。针对大风区段既有挡风墙“防车不防网”的不足,通过设计一种开孔式挡风墙,基于流体力学理论建立计算域模型,对挡风墙的防风效果进行评估,并仿真分析挡风墙孔隙率及开孔角度对于正馈线气动特性响应的规律。结果表明:挡风墙设置一定孔隙率后,会冲击挡风墙后形成的旋涡流场,使流场趋于平稳;随着孔隙率的增大挡风墙尾流接触网正馈线位置处气流增速区范围大幅减小,且正馈线气动力系数呈明显降低趋势;当挡风墙孔隙率为0.3时,挡风墙背风侧风速残余系数为0.46~0.69,此时正馈线升、阻力系数下降率分别超过41.56%和24.59%;在孔隙率为0.3,且挡风墙设置150°开孔角度时,正馈线气动力系数相较其他角度降幅明显,从而对于正馈线的舞动可以起到进一步的抑制作用。研究成果可为兰新高铁大风区段接触网正馈线舞动防治及挡风墙优化提供一定的理论参考。

The Lanzhou-Urumqi high-speed railway has suffered from wind disasters all year round.The construction of wind-break wall not only ensures the safety of train operation,but also intensifies the galloping of catenary positive feeder.In view of the deficiency of existing wind-break wall in gale areas that“only prevents trains but not catenary”.In this paper,a kind of perforated wind-break wall was designed,and a computational domain model was established based on the theory of fluid mechanics.The wind protection effect of the wind-break wall was evaluated,and the response laws of the porosity and opening angle of the wind-break wall to the aerodynamic characteristics of the positive feeder was analyzed by simulation.The results show that after the wind-break wall was set with a certain porosity,it will impact the vortex flow field behind the wind-break wall,making the flow field tend to be stable.With the increase of the porosity of wind-break wall,the range of the airflow growth zone at the positive feeder of the catenary decreases significantly,and the aerodynamic coefficient of the positive feeder shows a significant downward trend.When the porosity of the wind-break wall was 0.3,the residual coefficient of wind velocity at the leeward side of the wind-break wall was 0.46-0.69.At the same time,the drop rate of lift and drag coefficient of the positive feeder were more than 41.56%and 24.59%,respectively.When the porosity of the wind-break wall was 0.3 and the opening angle was 150°,the aerodynamic coefficient on the positive feeder decreases significantly compared with other angles,which can play a certain role in restraining the galloping of the positive feeder.The research results can provide a certain theoretical reference for the galloping prevention of the catenary positive feeder in gale areas of the Lanzhou-Urumqi high-speed railway.