山区高海拔大坡度单线隧道内动车组车内压力波动特性

Interior Pressure Fluctuation Characteristics of EMUs in High-Altitude, Steep-Gradient, Single-Track Mountain Tunnels

摘要: 以川藏铁路拉林段为背景研究高海拔、大坡度与特长隧道群多因素耦合作用下动车组车内压力的波动特性，基于一维可压缩非定常流动理论，建立了列车通过隧道时的外气动压力计算模型，并结合车辆动态密封性能的时间常数(τ)模型，构建了车内压力计算分析方法。通过对时速160公里动车组单车通过拉林段典型隧道进行全参数数值模拟，系统研究了密封等级(τ = 20 s)对车内压力关键参数的影响。结果表明，压力沿车厢纵向呈规律性分布：最大正压极值通常出现于头车，而最大负压与压力峰峰值则自头车向尾车递增。隧道结构参数中，线路坡度是加剧压力波动的关键，大坡度会显著提升压力幅值；海拔升高产生的低密度效应则对压力峰值有一定削弱。隧道长度影响波动模式，短隧道内压力变化剧烈，长隧道则呈现压力梯度累积与持续负压环境。研究发现，“大坡度”与“超长隧道”的组合最易诱发极端车内压力值，是风险最高的工况。本研究结论可为高海拔山区铁路的列车气密性设计、隧道断面与洞口结构的空气动力学优化提供直接的理论依据与数据支撑。

Abstract: Taking the Lhasa-Nyingchi section of the Sichuan-Xizang Railway as the research background, this study investigates the pressure fluctuation characteristics inside EMU carriages under the coupled effects of high altitude, steep gradient, and extra-long tunnel groups. Based on the one-dimensional compressible unsteady flow theory, an external aerodynamic pressure calculation model for trains passing through tunnels is established. Combined with a time constant (τ) model representing the dynamic sealing performance of the vehicle, an analytical method for calculating interior pressure was developed. Through full-parameter numerical simulation of a single 160 km/h EMU passing through typical tunnels in the Lhasa-Nyingchi section, the influence of sealing class (τ = 20 s) on key interior pressure parameters was systematically investigated. The results indicate that pressure distribution along the train length follows a clear pattern: the extreme maximum positive pressure typically occurs in the leading car, while the maximum negative pressure and the peak-to-peak value increase progressively from the leading car toward the trailing car. Among the tunnel structural parameters, the line gradient is the key factor exacerbating pressure fluctuations. Large gradients significantly increase the pressure amplitude. In contrast, the low-density effect resulting from high altitude somewhat mitigates pressure peaks. Tunnel length influences the fluctuation mode: pressure changes are acute in short tunnels, while long tunnels exhibit cumulative pressure gradients and a pronounced sustained negative pressure environment. The study finds that the combination of “large gradients” and “extra-long tunnels” most readily induces extreme interior pressure values, representing the highest-risk operational condition. The conclusions of this research provide direct theoretical basis and data support for the air-tightness design of trains, as well as for the aerodynamic optimization of tunnel cross-sections and portal structures on high-altitude mountain railways.