1-D Numerical Simulation For Unsteady Flow Generated By High-Speed Train Passing Through Tunnel

Traffic technology of high-speed trains is an important part of high-speed ground traffic technology. Research on aerodynamics of high-speed trains becomes significant problem which must be treated seriously, as the velocities of trains increase continually.Aerodynamics problem of high-speed trains consists of open-air aerodynamics problem and tunnel aerodynamics problem. The aerodynamics problem generated by train passing through tunnel is generally intenser and more serious than that generated by train running in the open. Therefore the research on aerodynamics is very significant. The result of the research on aerodynamics offers theory support for the R&D and evaluation of the high-speed track-train system.Various methods are developed for numerical simulation on the aerodynamics problem generated by train passing through tunnel. The problem is, in general, that of a 3-D, unsteady, turbulent, compressible flow, so analysis is rather daunting. However, the trains are huge and lathy objects, what is more, the tunnels are often rather long, in that case, some of the main features of these flows can be predicted well by idealized models. We can use 1-D, unsteady, compressible, non-isentropic flow models, if both the lengths of the train and the tunnel are far longer than the diameter of the tunnel. This method has predominance on facility and research efficiency.As the need of high-speed traffic increasing, maglev technology is attached importance to by researchers from every country, as a high-speed ground traffic technology possessing great potential. Research on the aerodynamics of the maglev is a very important program, because of the very high ground speed of maglev.In this paper, the author has developed the 1-D numerical simulation method for unsteady flow generated by high-speed train passing through tunnel, basing on the research on the aerodynamics of the maglev. The 1-D Euler equations with source terms are computed with finite volume scheme, this method is simpler on the boundary condition treatment, compared to the characteristics method. The model in this paper is flexible, can fit various tunnel conditions. And it can also solve the shock tube problem, in this paper, the Sod's shock tube problem has been computed as classical example to prove the model is good.The Patchway tunnel experimentation and single maglev passing through tunnel have been simulated. The flow generated by single high-speed train passing through tunnel has been amply analyzed, different influencing factors which maybe effect the flow have been considered. The compression waves and the expansion waves produced in the process of train passing through tunnel have complex characteristics, how they appear, propagate, reflect, lap and decay has been analyzed and study. Due to the flow generated by train passing through tunnel is complex 3-D flow with complex 3-D characteristics, 3-D numerical simulation is need for the further research on the tunnel aerodynamics.Besides, the situation of high-speed trains meeting in tunnel has been computed with 1-D numerical simulation, the situation of trains meeting in the tunnel with uniform section and the situation of trains meeting in the tunnel with non-uniform section have been studied.