高速列车隧道进口波辐射特征数值模拟研究
Numerical Simulation Study on the Radiation Characteristics of Tunnel Entry Waves Induced by High-Speed Trains

高速列车进入隧道时，除在隧道内形成传播的压缩波外，还会在隧道入口向外部空间辐射低频压力脉冲，即隧道进口波，其可能对隧道口周边环境与人员产生影响。为系统研究该压力波的辐射特性，本文基于三维非定常计算流体力学方法，对我国典型高速列车以350 km/h速度进入山体隧道工况下的进口波进行了数值模拟。计算采用雷诺平均Navier-Stokes方程，结合重叠网格技术及二阶空间和时间离散格式，通过动模型试验结果对数值方法的可靠性进行了验证。在此基础上，分析了列车头车与尾车进入隧道过程中隧道外压力波的时域演化特征、空间分布规律及频域组成。结果表明，进口波在隧道外空间中呈现明显的非对称辐射特性，其中头车进入隧道时产生的负压波幅值更大、影响范围更广，是外部环境压力波动的主要来源。隧道入口近场区域的压力变化同时受到列车绕流与进口波的共同影响，而远场区域的压力变化主要由进口波主导，并随距离增加呈近似球面扩散衰减。频域分析显示，压力波能量主要集中在次声及低频范围，可听频段占比较低，不同方位和距离处的声压级分布存在差异。研究结果可为高速铁路隧道入口区域的环境影响评估与减振降噪设计提供参考。
When a high-speed train enters a tunnel, low-frequency pressure pulses are directly radiated from the tunnel portal into the surrounding environment, in addition to the compression wave propagating inside the tunnel. These pressure waves, known as tunnel entry waves, may affect the environmental conditions near tunnel portals. In this study, three-dimensional unsteady computational fluid dynamics simulations were performed to investigate the radiation characteristics of tunnel entry waves generated by a typical high-speed train entering a mountain tunnel at a speed of 350 km/h. The Reynolds-averaged Navier-Stokes equations were solved using an overset grid technique with second-order spatial and temporal discretization schemes, and the numerical approach was validated against moving-model experimental data. Based on the validated model, the temporal evolution, spatial distribution, and frequency characteristics of pressure waves outside the tunnel during the entry of the head and tail cars were analyzed. The results show that the radiated pressure waves exhibit pronounced spatial asymmetry, with the negative pressure wave generated by the head car entry having a larger amplitude and wider affected region, dominating the environmental pressure response. In the near-field region, pressure variations are influenced by both train-induced flow and entry waves, whereas in the far field the pressure fluctuations are mainly governed by the entry waves and attenuate with distance in an approximately spherical manner. Frequency-domain analysis indicates that the wave energy is mainly concentrated in the infrasound and low-frequency range, with a limited contribution in the audible band. The results provide a reference for environmental impact assessment and noise mitigation design at high-speed railway tunnel portals.