Numerical Simulation Of Flow Characteristics Around High Speed Train Inside Tunnel

With the increasing of train speed, the aerodynamic problems of the high-speed train are becoming more and more important. The flow field in the tunnel will change tempestuously when the trains passing through it with a relatively high speed, which has a great effect on the stability, safety, passenger comfort, as well as the worker in the tunnel. Thus, it has a great meaning to study on the changes of flow field caused by the high-speed trains passing through the tunnels.This thesis is carried out with the commercially available flow simulation software STAR-CD which is based on the finite volume method, using the SIMPLE method of three-dimension steady incompressible flow Navier-Stokes equations with constant physical properties, comparing with the test data of typical foreign models, studying on the grid independence of numerical simulation on the ICE2high-speed train in the crosswind condition. The method of solution with QSKE turbulence model and MARS scheme is reliable, which is mainly carried on from the optimize of y+and changing the amount of streamwise or normal grid numbers. The simulation result of pressure distributing in the flow field, the side and lift force coefficient are compared with the open wind tunnel measuring date, indicating that the best result happens when the y+is50. Then the amount of grids are changed on purpose, which proves that the aerodynamic coefficient will not change a lot when the amount are in a certain range, achieving the independence. It provided the basis for the fourth chapter researching grid division of the flow characteristics in the tunnel, ensuring us a credible simulation result.Assuming the tunnel was infinitely long, the situation on the trains in the tunnel can be simulated, which can clearly display the pressure distribution of the same section by dealing with the typical tunnel cross-section pressure contour plot. Learning from the pressure contour plot of the head and rear of trains, the pressure all along the tunnel wall side is lower than the tunnel center side, meanwhile, the head, conjunction parts of the rear and straight body of trains have a large negative pressure, with the flow separation in existence. From the typical cross-section flow chart, the vortex can be seen generated on the conjunction part of the head and straight body, gradually developing and dissipating along the straight body, until disappeared on the conjunction part of the tail and straight body. By comparing the result of the IT models and OTI model, the pressure field distribution around the head and tail are mainly consistent, but there are some differences between the pressure value. By analyzing the unsteady flow calculation, the pressure difference exist around the train head and tail which changes cyclically, when increasing, it may cause the train lateral oscillatio This thesis can explain the flow characteristic of the trains inside tunnels by dealing with the pressure contour plot of the typical section and surfaces of trains, the streamline plot, C plot as well as the fluid dynamic knowledge. It is the first case home and abroad to have a further understanding about the generation, development and dissipation of the vortex by the streamline plot of a typical section. Therefore, this thesis can provide an important reference for unsteady simulation and revealing the flow characteristics for the future.