高速列车作用下道床表面风场特性研究

Wind Field Characteristics on Surface of Track Bed under Action of High-speed Train

道砟飞溅严重威胁高速铁路行车安全,其受道床表面风场特性影响明显。本文采用计算流体动力学方法,建立精确考虑轨道和车底外形的精细化仿真模型。基于验证后的模型,研究道床表面风速/风压空间分布规律,拟合分析行车速度、道床面高度和砟肩堆高对流场特性的影响,给出飞砟防治建议。研究结果表明:轨枕顶面和道心处风速/风压值较大,易发生道砟飞溅;轨道表面风压幅值与车速的平方成正比,与道床面高度、砟肩堆高成线性关系;若道床面高度、砟肩堆高均降低50mm,道床表面风压幅值将分别降低29.4Pa和9.7Pa,降低道床高度的效果更明显;道砟颗粒上、下表面压差是道砟飞溅发生的根本原因,可通过控制道床表面风压幅值、提高表层道砟稳定性等措施避免道砟飞溅。

Ballast flight seriously threats the operation safety of high-speed railway,which is influenced obviously by the wind field characteristics on the surface of track bed.The shape of ballast track or train underbody has a remarkable effect on ballast flight.A computational fluid dynamics method was used to establish a refined simulation model considering ballast track and train underbody shape.Based on the approved numerical calculation model,the spatial distribution of air velocity and air pressure on the ballast bed surface was studied to fit and analyze the influence of train speed,heights of ballast bed and ballast shoulder on the flow field characteristics.And a series of conclusions and preventive suggestions were made.The results show that the air velocity and air pressure are higher on the top of the sleeper as well as the central line of the track,which is easy to cause ballast flight.The maximum air pressure on track surface is proportional to the square of the train speed,which is linearly related to the height of ballast bed or ballast shoulder.A lower ballast level gives better results than a lower ballast shoulder as the maximum air pressure decreased 29.4 Pa and 9.7 Pa respectively when both ballast bed and ballast shoulder heights were decreased 50mm.The pressure difference between the to Pand bottom surface of ballasts is the major cause of ballast flight.Ballast flight can be prevented by taking measures such as controlling the maximum air pressure on the track surface or improving the stability of the ballast on top layer of the track.