不同海拔高度环境下高速列车气动特性研究

Research on the Aerodynamic Characteristics of High-speed Trains in Different Altitude Environments

高海拔地区气候环境相对恶劣,海拔越高,空气压力、温度及密度越低。因此,研究高速列车在高海拔运行环境下的气动特性对列车运行安全性及高海拔地区铁路建设具有重要意义。以某型号高速列车为研究对象,对明线单车、明线会车及隧道通过运行工况进行气动数值模拟计算,研究不同海拔高度下列车的气动载荷及交变压力特性。研究结果表明,明线单车运行高速列车的气动阻力及气动升力都随海拔的增加而降低,但气动阻力系数及气动升力系数基本不随海拔的增加而改变,气动阻力系数中的压差阻力系数随海拔的增加而减小,黏性阻力系数随海拔的增加而增大。不同海拔高度下列车交会压力波及隧道压力波变化规律一致,但压力波幅值随海拔高度的增加而减小;列车交会压力波峰值和隧道通过的列车压力波、出口微气压波都与海拔高度呈现较强的相关性。此外,海拔高度增加带来的温度变化使压力波的传播速度降低,导致不同海拔高度下隧道压力波及出口微气压波出现滞后现象。

The environment in regions with high altitudes is relatively harsh,and the greater the altitude,the lower the air pressure,temperature and density.Therefore,the study on the aerodynamic performance of the high-speed train running in high-altitude regions is of great significance to the running safety of the train and the construction of the high-altitude railway.Taking a high-speed train as the research object,the aerodynamics of the single train,trains passing each other in the open air and the train passing through a tunnel are carried out to study the aerodynamic loads and transient pressure characteristics of the train at different altitudes.The results show that the aerodynamic drag and lift force of the high-speed train decrease with the increase of altitude when the train is running in the open air.However,the aerodynamic drag and lift force coefficients do not change basically with the altitude increase.The pressure drag force coefficient of the aerodynamic resistance coefficient decreases with the altitude increase,whereas the viscous drag force coefficient increases.The pressure waves of trains passing each other and passing through the tunnel for different altitudes have the same changing law,respectively.However,the amplitude decreases with the increase in altitude.Meanwhile,the peak values of the pressure wave generated by trains passing each other have a direct correlation with altitudes,and so are the pressure waves,the micro-pressure waves at the tunnel exit generated by the train passing through the tunnel.Moreover,the temperature change caused by the increase in altitude reduces the speed of sound,thereby reducing the propagation speed of the pressure wave.As a result,the pressure wave in the tunnel and the micro-pressure waves at the tunnel exit appear hysteresis at different altitudes.