风攻角对车-桥系统气动特性及耦合振动的影响

Influence of wind attack angle on aerodynamic characteristics and coupled vibration of vehicle-bridge system

为研究强风作用下风攻角对车-桥系统气动特性以及车桥耦合振动的影响,以某大跨度铁路悬索桥为研究对象,通过节段模型风洞试验测得在不同风攻角条件下的车、桥气动力并探寻其受风攻角变化影响的规律。依据弹性系统动力学总势能不变值原理进一步建立可考虑风荷载作用的车-桥系统耦合振动方程,求解方程并就风攻角变化对桥梁和列车的动力响应的影响进行分析研究。研究结果表明:风攻角对由悬索桥和列车组成的车-桥系统的气动特性影响较大。当风攻角向负向增大时,桥梁阻力系数增幅较大;当风攻角向正向增大时,桥梁阻力系数增幅较为平缓;当风攻角绝对值较大时,车辆阻力系数较大并在风攻角为-8°时有最大值。强风下车-桥系统耦合振动响应对风攻角的变化较为敏感,当风攻角为-8°时,桥梁主跨跨中处横向及竖向振动位移有最大值,列车动力响应极大值多在风攻角较大时出现。列车在桥面横向上位置的变化对车辆和桥梁的气动特性有明显的影响,迎风工况中车、桥阻力及升力系数均在一定程度上大于背风工况,列车位置变化对车桥耦合中车辆、桥梁的动力响应也有较大的影响。

To study the effect of wind attack angle on aerodynamic characteristics of the vehicle-bridge system and the vehicle-bridge coupling vibration under strong wind, taking a long-span railway suspension bridge as the background, the aerodynamic forces of vehicle and bridge at different wind angles of attack were measured through segmental model wind tunnel tests. The law affected by the change of angle of attack was explored.Then, according to the principle of the total potential energy with stationary value in elastic system dynamics, the vibration equation of the vehicle-bridge coupling system considering wind loads was further established. The vibration equation was solved and the effect of wind attack angle on the dynamic response of the bridge and train was analyzed. The results show that the wind attack angle has a great influence on the aerodynamic characteristics of the vehicle-bridge system composed of the suspension bridge and train. When the wind attack angle increases in the negative direction, the bridge drag coefficient increases greatly.When the wind attack angle increases in the positive direction, the bridge drag coefficient increases slowly. When the absolute value of the wind attack angle is large, the vehicle drag coefficient is large. It has a maximum value when the wind attack angle is-8°. The coupling vibration response of the vehicle-bridge system in strong wind is sensitive to the change of wind angle of attack. When the wind angle of attack is-8°, the transverse and vertical vibration displacement at the middle of the main span of the bridge has the maximum value, and the maximum value of the train dynamic responses mostly appears when the wind attack angle is large. The change of the train’s position in the transverse direction of the bridge deck has a significant impact on the aerodynamic characteristics of the train and bridge. The drag and lift coefficients of the train and bridge under windward condition are greater than those under leeward condition to a certain extent. The change of train position also has a greater impact on the dynamic response of the vehicle and bridge in vehicle bridge coupling.