高速铁路隧道内外压力脉动数值模拟用边界条件的研究

Study of Boundary Conditions for the Numerical Simulation of Pressure Fluctuation Inside and Outside of a High-Speed Railway Tunnel

高速列车通过隧道将诱发隧道内外的压力脉动,其中包括隧道内压力波和隧道进出口波。在对这两类空气动力学现象同时进行数值模拟时,会产生有关开放边界和隧道出口端边界的选用问题。文章基于三维可压缩非定常湍流流动模型,采用CFD软件中的滑移网格技术,模拟高速列车穿过隧道的全过程。通过改变两种计算区域隧道远场开放边界条件以及隧道出口边界条件,考察了其对隧道内压力波以及进口波计算结果的影响特性,得出了开放边界对进口波影响较大,出口边界对隧道压力波影响较大。研究进出口波时,开放边界采用黎曼边界条件较合适;研究隧道压力波时,出口边界采用压力边界条件较合适。

When a train passes through a tunnel at a high speed, it will induce a pressure fluctuation inside and outside of the tunnel, including a pressure wave inside the tunnel and another at the tunnel entrance/exit. In a numerical simulation of these two aerodynamic phenomena, the selection of open boundary conditions and boundary conditions at the exit portal were critical. Based on a 3D compressible unsteady turbulence flow model, the sliding mesh technique of the CFD code was adopted to simulate the entire process of a high-speed train passing through a tunnel. The impacts on the calculation results for pressure waves inside the tunnel and at the tunnel entrance/exit induced by changing the open boundary conditions and the exit boundary conditions in two calculation domains were studied. The results show that the open boundary condition has a major impact on the wave at the tunnel entrance, as does the exit boundary condition on the tunnel pressure wave. Riemann boundary conditions are appropriate for the open boundary while studying the wave at the entrance/exit, and the pressure boundary conditions are appropriate for the exit boundary while studying the tunnel pressure wave.