川藏铁路线路坡度对动车组隧道通过气动性能的影响

Influence of Sichuan-Tibet Railway Line Gradient on Aerodynamic Performance of EMU Train Passing Through a Tunnel

为研究川藏铁路线路坡度对长大隧道内运行动车组气动性能的影响,采用一维可压缩非定常不等熵流动模型和广义黎曼变量特征线法,对列车通过不同坡度的长大隧道气动性能进行数值计算,分析了线路坡度对列车通过隧道时气动阻力及压力波的影响。研究结果表明:上坡通过隧道的列车头尾车车外压力随坡度增大呈减小趋势;下坡通过隧道的列车头尾车车外压力随坡度增大呈增大趋势;列车上坡通过隧道时平均阻力明显大于相同坡度下坡时的平均阻力;上坡通过隧道时气动阻力最小值出现在列车车头驶入隧道时刻,气动阻力最大值出现在车尾驶入隧道诱发的膨胀波传至车头时刻;平直坡道通过隧道的列车气动阻力在一定时间段维持恒定,而上下坡通过隧道的列车气动阻力达到最大值后一直呈减小趋势。

In order to research the Sichuan-Tibet railway line gradient on the aerodynamic performance of the EMU train running in a long tunnel,the one-dimensional compressible unsteady non-homentropic flow model and the method of characteristics of generalized Riemann variables are used to numerically calculate the aerodynamic performance of the train passing through long tunnels with different line gradients.The influence of line gradients on the aerodynamic resistance and the pressure wave of the train passing through tunnels is analyzed.Results show that the outside pressures on the head coach and the tail coach of the train passing through a uphill tunnel tend to reduce with the increase of the gradient.However,the outside pressures on the head coach and the tail coach of the train passing through a downhill tunnel tend to increase with the increase of the gradient.The average resistance of the train passing through the uphill tunnel is significantly larger than that of the train passing through the downhill tunnel with the same gradient.The minimum of the aerodynamic resistance of the train passing through the uphill tunnel emerges at the moment when the train head nose runs into the tunnel portal.The maximum of the aerodynamic resistance of the train emerges at the moment when the expansion wave induced by the train tail running into the tunnel propagates to the head nose.The aerodynamic resistance of the train passing through a straight and horizontal tunnel keeps constant in a period of time.while the aerodynamic resistance of the train passing through a uphill or a downhill tunnel continue to reduces after it reaches the maximum.