横风下高速列车非定常空气动力特性研究

通过大涡模拟(LES)数值计算方法,对均匀定常横风下高速列车的非定常空气动力特性进行了研究。计算得到横风下列车车体所受空气动力的时域及频域特性、列车周围非定常流动结构及相应非定常流场特性。对计算结果分析表明,即使在均匀定常横风下,列车所受空气动力也存在明显的非定常性。对于所研究车型,这种非定常空气动力的特征频率出现在11 Hz以下,并且主要峰值集中在0~3 Hz区间,这与列车系统本身的固有振动模态频率接近,存在横风引起列车系统共振,进而发生列车倾覆的可能;同时研究表明,横风下列车周围流场非定常特性与列车所受非定常空气动力特性在频域中存在对应关系,可以通过测量非定常流场确定列车非定常空气动力特性。

Study on the Unsteady Aerodynamic Characteristics of a High-speed Train Under Cross Wind

The unsteady aerodynamic characteristics of a generic high-speed train under cross winds are studied numerically by the large eddy simulation(LES) method.The characteristics of the aerodynamic forces on the train,and the structures and characteristics of the flow field around the train are presented.The numerical results indicate that the aerodynamic forces on the train have strong unsteady characteristics even when the cross wind is constant;the dominating frequencies of the aerodynamic forces are below 11 Hz with the leading peaks in the range between 0 and 3 Hz,which are very close to the resonant frequency range of the train.It is thus possible that the train as a dynamical system will be resonated by the unsteady aerodynamic forces due to the cross wind and the resonance could lead to the overturning of the train.The frequency characteristics of the flow field around the train and the frequency characteristics of the unsteady forces on the train were found to be the same,and consequently the unsteady characteristics of aerodynamic forces on the train could be studied by measuring the unsteady characteristics of the flow field around the train.