隧道摩擦效应对高速铁路隧道压缩波传播与演变的作用机理

The pressure wave and micro-pressure wave of the high-speed railway tunnel have important impacts on the safe operation of high-speed trains, passenger comfort and tunnel environment. The study for propagation process of compression wave is the key to predict and mitigate pressure wave and micro-pressure wave. Tunnel friction effect is an important factor of wavefront evolution during compression wave propagation. At present, the mechanism of tunnel friction effect on wavefront evolution is not clear and there is not accurate and reasonable calculation model. This project will research the physical process of transition of unsteady flow boundary layer between the toe and heel of wavefront using theoretical analysis and direct numerical simulation, reveal the mechanism of tunnel friction effect on wavefront evolution, establish the calculation model of tunnel friction effect and the numerical method of wavefront propagation which will be checked by model test. Meanwhile, based on the above method, the influences of nonlinear effect and tunnel friction effect on wavefront evolution are distinguished and their influence weights are quantified, the relationship between the critical tunnel length and train speed, parameters from tunnel wall is obtained, the theoretical formulas of the amplitude and maximum pressure gradient of compression wave are derived. The research results will benefit aerodynamics theory of high speed railway tunnel and the design of countermeasures for reducing pressure wave and micro-pressure wave.

高速铁路隧道压力波和微压波对高速列车运行安全、司乘人员舒适性和隧道周围环境都具有重要影响。压缩波传播过程的研究是预测、减缓隧道压力波和出口微压波的关键。隧道摩擦效应作为影响压缩波传播过程中波形演变的重要因素之一，其对压缩波波形演变作用机理尚不明确，且无准确合理的计算模型。本项目拟采用理论分析和直接数值模拟的方法研究压缩波前后非稳态流动边界层过渡的物理过程，揭示隧道摩擦效应对压缩波传播特性和波形演变的作用机理，建立隧道摩擦效应的计算模型和压缩波传播的数值计算模型及方法，并通过模型试验验证。基于上述研究方法，明确非线性效应和隧道摩擦效应对波形演变影响机制的差异，量化各效应的影响权重，得到反映临界隧道长度与列车速度及隧道壁面参数之间的关系式，推导压缩波幅值和最大压力梯度的理论计算公式。研究成果对于完善高速铁路隧道空气动力学理论、制定隧道压力波和微压波减缓措施具有重要的理论意义和实用价值。

隧道初始压缩波是形成隧道微压波的起因，而压缩波在隧道内的传播及演变则是决定出口微压波幅值的关键。不同传播距离下压缩波的传播与演变规律，可用于隧道长度设计及微压波减缓措施的制定。本项目设计并搭建了隧道压力波模型实验台，开展了不同列车运行速度的模型实验，掌握了隧道压力波的影响因素。建立了隧道压力波的三维CFD数值计算的方法，并采用模型实验和理论方法对其进行了验证。采用三维CFD数值计算模型，探讨了湍流模型、壁面粗糙高度、流体的粘性和初始压缩波的瞬时加速度等对波形演变的影响。基于一维、可压缩、非定常和不等熵的流动模型，建立了压缩波传播的有限体积法计算程序，并采用模型实验和现车实验验证了计算程序。采用该计算程序分析了长传播距离下流体的运动粘度、隧道内空气的初始温度以及初始压缩波的瞬时加速度对变形率和衰减率的影响，掌握了各参数对波形演变特性的影响规律。分析了非线性效应、隧道稳态摩擦效应和非稳态摩擦效应对波形演变的作用机理，量化了各效应对波形演变的影响权重，研究了不同列车速度和不同阻塞比下波形的演变规律。研究结果表明稳态摩擦主要影响压缩波的幅值，而非稳态摩擦主要影响其压力梯度；稳态摩擦作用使最大压力梯度上升时间短的波形变形率更大，非稳态摩擦作用使最大压力梯度上升时间长的波形变形率更大；列车速度越高或阻塞比越大，最不利隧道长度越短。本项目的研究成果对高速铁路隧道设计、列车提速及微压波减缓措施的制定具有重要的指导意义。