Numerical Simulation And Analysis Of High-Speed Train In Multiphase Flow Based On Lagrangian-Eulerian Scheme

Nowadays during the fast development of high-speed train industry in China, the faster the speed can achieve the more complex the aerodynamics characteristics will become. In the future the railway nets will constantly extend and the climate environment in China is complicated and changeable, the safety issues need to be investigated during the running in the extreme weather condition. This research is conducted based on the steady-state incompressible Navier-Storkes equation, standard k-εturbulence model, and Lagrangian-Eulerian scheme in multiphase flow. The high-speed train running in open air, in the rain and hail environment is simulated through Fluent.Firstly build up the model of high-speed train with different components such as windshield, bogie and pantograph. Solving the governing N-S equations and turbulence model, the train with the speed of 270km/h running in open air is studied. We calculate the pressure in the around flow field, analyze the drag force and the lift force with their coefficients, and also compare the results with the experimental data for validation. Results show the affects of those different components on the aerodynamics, along with the causes at the local flow field. This research could help the future design of the train outline to reduce the drag force.Secondly we use the Discrete Phase Model (DPM) in Fluent to study the train aerodynamics in multiphase flow of rain and hail. This numerical model is based on the combination of the Eulerian and Lagrangian methods, and validated by good agreement between the experiment and numerical simulation results of NACA airfoil performance in heavy rain. Using the validated scheme, we conduct the numerical simulation of high-speed train running in the heavy rain and hail environment. Then we compare the aerodynamic performances such as drag, lift and cross force with the running condition in open air and in multiphase flow. The influence of the second phase on the safety problem is investigated. Moreover, we also consider the particles distribution around the train surface and explain the cause of those phenomenon. At the end, we provide some theory support for the safety issues.