真空管道磁悬浮列车气动特性及激波效应三维研究

Three-dimensional study on aerodynamics characteristics and shock wave effects of the vacuum tube train

近年来,真空管道列车系统以其减阻降噪、高速运行的特点成为高速列车新的研究方向。真空管道列车运行环境复杂多变,对管道内部气动特性及流场结构的研究在真空管道列车的设计和优化中尤为重要。研究基于SST k-ω湍流模型及大涡模拟方法,采用三维数值模型对阻塞比为0.15的真空管道磁悬浮列车系统在马赫数为0.490~0.980的来流条件和0.3~0.1 atm的管道压力下进行稳态和非稳态模拟,得到列车周围外部流场的气动特性,详细阐述了列车尾流激波的形成和传播。根据不同来流马赫数和压力条件将流场分为3类典型工况,并沿流动方向将流场分为5个区域分析流场特性。结果表明,随着来流马赫数从0.490增加到0.654,尾车肩部开始出现激波。随着来流马赫数进一步增加至0.817,尾流区域出现斜激波、“X”型激波结构等复杂流动现象,不同来流马赫数条件下跨声速流场中的气流马赫数分布相似,压力系数呈现梯度分布。激波与尾涡、边界层相互干涉与融合,成为尾流流场的主要结构。研究成果可为真空管道列车不同来流速度和不同真空度情况尾流激波抑制以及气动阻力优化设计提供工程指导。

The Vacuum Tube Transportation(VTT) system has become a new research direction of high-speed train due to its characteristics of drag and noise reduction and high-speed operation. The operating environment of VTT is complex and changeable. Studying the aerodynamic characteristics and flow field structure inside the tube is particularly important in the design and optimization of VTT. Based on the SST k-ω turbulence model and Large Eddy Simulation method, the three-dimensional numerical model of VTT was employed for steady and unsteady VTT simulations with blocking ratio of 0.15, Mach number of 0.490~0.980, and pressure of 0.3~0.1 atm. The aerodynamic characteristics of external flow fields around the VTT were examined. The formation and propagation of shock waves in the wake of the VTT were elaborated. Three typical types of flow field can be distinguished based on the variations of Mach number and pressure. The flow field was divided into five areas along the flow direction to analyze the characteristics of the flow field. The results indicate that as the incoming Mach number increases from 0.490 to 0.654, shock waves appear on the shoulder of the tail car. The incoming Mach number increases from 0.654 to 0.817, complex flow phenomena such as oblique shock and “X” type shock appearing in the wake and similar Mach number distributions with different incoming conditions. The pressure coefficient exhibited a gradient distribution. The shock waves interfered and merged with the vortices and boundary layers,thus becoming the main structure of the flow field in wake. The research results can provide engineering guidance for wake shock suppression and aerodynamic drag optimization design of VTT with different levels of inlet velocity and vacuum degree.