风屏障布局对公铁同层桁架桥-列车系统气动特性的影响

Effect of layout of wind barriers on aerodynamic characteristics for the same-story truss bridge-train system

为研究风屏障布局对公铁同层桁架桥-列车系统气动特性影响,以高为2.5 m、透风率为30%的风屏障为例,对某大跨度公铁同层钢桁架悬索桥进行节段模型风洞试验,测试不同风屏障布置形式(单、双侧)和布置位置(内、外侧)条件下车桥系统气动特性。研究结果表明:当风屏障布置在主梁外侧时,风屏障对主梁阻力系数的影响大于其布置在内侧时的影响,风屏障对列车的遮挡效果也比风屏障布置在内侧的遮挡效果好;下游内侧风屏障对车桥系统气动特性几乎无影响,但下游外侧风屏障不仅会增大主梁阻力系数,同时能减小列车升阻力系数,影响列车各面风压特别是背风面负压区;在该桁架桥外侧布置双侧风屏障时,主梁阻力系数仅增大10%,而列车阻力系数减小55%,风屏障效果较好。

To study the effect of the layout of the wind barrier on the aerodynamic characteristics of the same-story truss bridge-train system,a wind tunnel test with a scale model of large-span road-rail same-story truss suspension bridge was carried out.Taking the 2.5 m high wind barrier with 30%porosity as an example,the aerodynamic characteristics of the train-bridge system with different wind barrier layout forms(single and double sides)and with layout positions(inside and outside)conditions were tested.The results show that when the wind barrier is arranged on the outside,the influence on the resistance coefficient of the main girder is greater than that when the wind barrier is arranged on the inside,and the shielding effect on the train is also better than that on the inside.The downstream inner wind barrier has almost no effect on the aerodynamic characteristics of the vehicle-bridge system,but the downstream outer wind barrier increases the drag coefficient of the main girder,reduces the lift drag coefficient of the train,affects the wind pressure of the train,especially the negative pressure area on the leeward surface of the train.When the double-side wind barrier is arranged on the outside of the truss bridge,the resistance coefficient of the bridge is only increased by 10%,while the drag coefficient of the train is reduced by up to 55%,which indicates that the better wind barrier effect is good.