Abstract: Aerodynamic effect has become one of the key restrictive factors for the further speed increase of high-speed trains, and high-speed operation has led to a sharp increase in energy consumption and environmental noise hazards. In order to develop the next generation of higher-speed transportation systems, the concept of a transportation system combining low-vacuum pipelines and high-speed maglev trains has been proposed and developed. However, some specific flow phenomena including the shock wave effect appear as the high speed train passing through the low-vacuum pipeline at an ultra-high speed. Scientific and engineering issues such as the shock wave evolution mechanism in long pipelines, the influence of the train shape, the system mode and other parameters on the shock wave flow field of pipeline trains need to be explored. By analyzing the characteristics of the flow field around the train, the three-dimensional shock wave structure, the pressure on the internal pipeline wall and the train surface, the surface temperature and aerodynamic resistance of the train, the effect of different shapes and system modes on the shock wave, the aerodynamic resistance and other physical variables is explored. Results show that the train shape and the system mode have significant influence on the generation position, shape length, reflection position, special curve and intersecting line of the shock wave, meanwhile affect the train aerodynamic drag and other physical variables. When the length of the train is identical, the aerodynamic drag coefficient, the surface pressure coefficient and the surface temperature of the train decrease with the increase of the streamlined length of the train nose under the effect of shock waves inside the pipe. However, the influence of the rail transit system mode is relatively slight comparing with the parameter of train shape.

Key words: maglev train, shape, system mode, pipeline train, shock wave field