铁路隧道内设置缓冲气室的流动特性研究

Flow characteristics of an air chamber in a rail tunnel

铁路隧道内设置气室可以减轻列车鼻尖波在传播过程中产生的惯性陡变,并有效地防止隧道洞口出现严重的微气压波。该方法的有效性通常与缓冲气室的压力响应和附近流动特性密切相关。本文基于无黏、轴对称流动模型,对典型波前作用下隧道内单个气室的流动特性进行了数值研究。研究结果表明:对于一个固定体积的气室来说,其连接处尺寸存在一个确定的区间,可以使气室呈现欠阻尼特性;连接处流动的不均匀性会导致气室和隧道内的压力分布呈现一定的三维效应;轴对称模型和一维模型所得最大压力梯度之间的差异主要发生在气室连接处;当波前通过气室约5 m后,该差异逐渐减小至1%左右。此外,我们还通过建立缩比模型实验装置,对比了数值结果和实验结果,验证了数值方法的准确性。

In this paper,the flow characteristics of an air chamber inside a tunnel when subjected to train-nose-entry wavefronts were analyzed using numerical simulation.The results demonstrate that there exists a specific range of connection sizes for a fixed volume of air chamber,which imparts an under-damped characteristic to the chamber.Additionally,the pressure distribution within the air chamber and tunnel exhibits a noticeable three-dimensional effect as a consequence of the non-uniform flow field at the connection of the air chamber.The difference in the numerical results of the maximum pressure gradient is primarily observed at the air chamber connection when comparing the axisymmetric model to the one-dimensional model.However,this difference gradually diminishes to approximately 1%after the wavefronts have traversed through the air chamber for a distance of approximately 5 m.Furthermore,a scaled experimental setup was constructed to compare the obtained numerical results with the experimental data,successfully validating the accuracy of the numerical method.