Abstract
With the world development of high-speed railways and increasing speeds, aerodynamic forces and moments acting on trains have been increased further, making trains stay at a “floated” state. Under a strong crosswind, the aerodynamic performance of a train on the embankment is greatly deteriorated; lift force and horizontal force borne by trains will be increased quickly; trains may suffer derailing or overturning more easily compared with the flat ground; train derailing will take place when the case is serious. All of these phenomena have brought risks to people’s life and properties. Hence, the paper establishes an aerodynamic model about a high-speed train passing an air barrier, computes aerodynamic forces and moments, and analyzes pulsating pressures on the train surface as well as those of unsteady flow fields around the train. Computational results indicate that when the train passed the embankment air barrier, the head wave of air pressure full wave is more than the tail wave; the absolute value of negative wave is more than that of the positive wave, which is more obvious in the head train. When the train is passing the air barrier, pressure pulsation values at head train points are more than those at other points, while pressure changes most violently at the train bottom, and pressure values close to the air barrier are more than those points far from the air barrier. Pressure values at the cross section 1 were larger than those of other points. Pressure values at measurement points of the tail train ranked the second place, with the maximum negative pressure of 1253 Pa. Pressure change amplitudes and maximum negative pressure on the train surface are increased quickly, while pressure peak values on the high-speed train surface are in direct ratio to the running speed. With the increased speed of the high-speed train, when it is running in the embankment air barrier, the aerodynamic force and moment borne by each train body are increased sharply, while the head train suffers the most obvious influences of aerodynamic effects.
Highlights
With the increase of the train speed, the high-speed running of a train will motivate motion of air around the train
Li et al conducted optimized simulation of appearance of open-hole wind-shielding walls on high-speed railways located at the embankment, obtaining influences brought by factors such as hole shape, hole layout mode, aperture ratio, and hole diameter to aerodynamic performance of the D-series highspeed train
The following conclusions were obtained: (1) The maximum positive pressure of the whole train was located at the nose tip of the head train; the maximum negative pressure of the whole train was distributed at the head train pilot
Summary
With the increase of the train speed, the high-speed running of a train will motivate motion of air around the train. Gao and Duan used two-dimensional models to research influences brought by single-sided and double-sided wind-shielding walls with different heights on the single line to aerodynamic performance of trains, but the research results could not reflect three-dimensional effects of flow fields around rain bodies. Li et al conducted optimized simulation of appearance of open-hole wind-shielding walls on high-speed railways located at the embankment, obtaining influences brought by factors such as hole shape, hole layout mode, aperture ratio, and hole diameter to aerodynamic performance of the D-series highspeed train. Structural form, installation mode, position, height, and other properties of the wind-shielding wall structure may not be applicable to bridges on the passenger transport lines (high-speed railways) in wind areas. Unsteady flow characteristics, aerodynamic force, and aerodynamic moment characteristics embodied when the high-speed train passed the embankment air barrier were researched in details. This paper provides some engineering references for the structural optimization design, rational layout of air barriers, computing aerodynamic load intensity, and so forth concerning the high-speed train passing the air barrier
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