基于大涡模拟的横风下高速列车非定常气动载荷特性

摘要

为研究横风环境下高速列车的非定常气动载荷特性,基于大涡模拟方法建立高速列车三维绕流流动数学物理模型,研究不同横风风速及不同车速下高速列车非定常气动载荷的时域特性、频域特性、组成特性及脉动特性.计算结果表明:横风下高速列车气动载荷具有明显的非定常特性,简化中心的选择会影响气动力矩的非定常特性.从气动载荷的变异系数来看,侧力、侧滚力矩和摇头力矩的非定常现象随侧偏角的增加而增大,倾覆力矩与点头力矩的非定常现象随侧偏角的增加而减小,而升力的非定常现象随侧偏角的增加先增大后减小.频谱分析表明,头车非定常气动载荷的峰值频率与流线型车头、车身非定常气动载荷的峰值频率有很好的对应关系.高速列车非定常气动载荷的主要峰值频率集中在0～5 Hz,这与高速列车系统本身存在的一些固有振动频率接近,存在由于横风引起列车系统共振,进而发生列车倾覆的可能性.%In order to study the characteristics of unsteady aerodynamic loads of a high-speed train under crosswinds,the mathematical and physical models of the three dimension flow filed of a high-speed train were established by large eddy simulation.The characteristics of unsteady aerodynamic loads of a high-speed train were studied under different crosswind speeds and at different train speeds,which included the characteristics of the time domain,the frequency domain,the composition and the pulsation.The computational results show as follows:The aerodynamic loads of a high-speed train under crosswinds have strong unsteady characteristics; the choice of the reduction center affects the unsteady characteristics of aerodynamic moments.From the angle of the coefficient of variability (CV) of unsteady aerodynamic loads,the unsteady levels of the side force,roll moment and yaw moment arise with increasing of the yaw angle,the unsteady levels of the capsizing moment and pitch moment reduce with increasing of the yaw angle and the unsteady levels of the lift force first arise and then reduce with increasing of the yaw angle.The frequency analysis shows as follows:There is a good corresponding relation between the peak frequencies of unsteady aerodynamic loads of the head car and the peak frequencies of unsteady aerodynamic loads of the streamlined head and car body; the peak frequencies of a highspeed train lie mainly in the range of 0～5 Hz,which are close to the natural vibration frequency of a high-speed train and so possibly cause the train under crosswinds to be resonated and even overturned.