钢桁梁桥上列车双车交会气动特性风洞试验

为探究横风作用下钢桁梁桥上列车双车交会过程中气动力系数的突变机理，以某一大跨度公铁两用钢桁梁桥为背景，首先根据XNJD-3风洞实验室的尺寸设计了一套移动车辆模型试验系统；然后根据风洞阻塞比的要求设计了几何缩尺比为1∶30的桥梁和车辆试验模型；最后测试了横风作用下桥上列车交会过程中移动车辆模型的气动力。为尽可能地降低试验系统对运动车辆气动力的干扰，对原始时程数据进行了低通滤波处理，并分析了车速、风速、合成风向角、车辆所在轨道位置等因素对车辆气动力系数的影响。试验结果表明：双车交会时，背风侧运动车辆的气动力系数具有明显的突变趋势，迎风侧运动车辆的气动力系数变化较为平稳；列车交会时突变区域主要受运动车辆引起的列车风速的影响，且随车速的增加而增大，横风风速对突变区域影响较小；交会过程中背风侧车辆升力系数和侧向力系数的突变量随合成风向角的增大呈增大趋势，力矩系数突变量对合成风向角的变化不敏感；横桥向列车所处轨道位置影响其气动力系数。试验结果可为研究横风作用下高速列车-桥上交会过程的行车安全提供数据支持。

Wind Tunnel Measurement of Aerodynamic Characteristics of Trains Passing Each Other on Truss Bridge

To investigate the mutation mechanism of the aerodynamic coefficient of trains passing each other on truss bridge under cross wind, a highway-railway steel truss bridge was selected for study. First, a set of mobile vehicle models was designed, accounting for the size of the XNJD-3 wind tunnel test room. Next, a bridge and vehicle test model was designed, based on the wind tunnel blocking ratio and a geometric scale ratio of 1:30. Finally, the aerodynamic forces of trains passing each other on the truss bridge were tested under the cross wind. In order to reduce the interference of the test system to the aerodynamic forces of the moving vehicle as much as possible, low-pass filtering was performed on the original time history data. The influences of factors such as vehicle speed, wind speed, yaw angle and vehicle orbital position on the aerodynamic coefficients of the vehicle were analyzed. The results show that when two trains pass each other, the aerodynamic coefficients of the vehicle running on the leeward side of the deck have an obvious trend of mutation, while those of the vehicle running on the windward side vary smoothly. The mutation region is mainly affected by the speed of the wind induced by passing trains and enlarges with an increase in vehicle speed; it is not significantly influenced by cross wind velocity. The variation of lift and side force coefficient of the intersecting vehicle on the leeward side tends to be magnified with increasing yaw angle, while the variation of rolling moment coefficient is not sensitive to changes in yaw angle. The rail position of the running train in the transverse direction also has an impact on the aerodynamic coefficients. The test results provide data support for study on the driving safety of high-speed trains passing each other on truss bridge under cross wind.