【作者】 郗艳红；

【导师】 贾力； 毛军；

【作者基本信息】 北京交通大学 ， 流体力学， 2012， 博士

【摘要】 高速列车具有十分复杂的三维几何外形和大长细比,在高速运行时形成复杂的、强非线性的三维粘性绕流流动。与在无风环境中相比,列车遇到横风时,其绕流流场和气动特性将发生剧烈变化,轮轨动力学性能亦随之改变,使列车的运行安全受到影响。目前,国内外针对高速列车横风效应和气动安全性的研究己取得诸多成果,但在复杂场景建模、横风气动力分析、横风效应的非定常性质,以及横风气动特性对列车运行安全的影响等方面的研究还需进一步深入。本文通过理论分析、模型实验、流动数值模拟和多体动力学仿真相结合的方法,以CRH型高速列车原型为研究对象,对列车的横风气动特性和相应的车辆轨道动力学问题进行了数值模拟与仿真分析,探讨了横风作用下的列车运行安全控制问题。主要内容包括以下几部分：1、研究了单列高速列车在明线横风环境中运行的气动特性。结果表明：使用均匀风和大气底层边界速度型两种风场计算的列车气动作用力相差20%-60%,差值大小与平地、路堤和桥梁等路面条件以及车辆位置相关,使用均匀风评估列车的横风安全性将与实际情况存在较大偏差。横风风速和风向角以及车速对列车气动特性的影响规律可用三次多项式函数来描述,且对头车气动特性的影响最明显。气动阻力系数与车速、风速和风向角之间的关系可用无量纲量综合公式描述；对于编组车辆数量不同的列车,头车气动性能基本相同,三节车辆编组列车的气动安全性在一定程度上能够适用于三节以上车辆编组列车的气动安全性评估。受电弓装置和转向架的气动荷载占各节车辆气动力的份额可达10-20%,不宜忽略。2、采用分离涡模拟法模拟了恒定风场中高速列车绕流的非定常流动,在时域和频域内分析了车辆和转向架气动特性的瞬态性质。结果表明：在恒定来流中,列车的背风侧和尾车的尾迹区存在着强度不同、空间几何尺度各异并随时间随机变化和脉动的分离涡；各节车辆的非定常气动荷载的时均值与按整场定常流动计算得到的结果基本一致,但瞬态荷载峰值却比时均值高出较多；振幅频谱和功率谱密度的最大峰值所对应的频率不尽相同,但都集中在0-4Hz内,处于某些列车部件的固有频率范围内。头车的横向力和倾覆力矩的分布频率范围较大,与车体自身频率耦合的范围较宽,横风气动安全性较差。各个转向架气动荷载的功率谱密度的最大峰值所对应的频率也不相同,但都集中在0.5-3.5Hz内。3、采用移动网格原理对列车交会进行了数值模拟计算。分析了高速列车在明线交会的气动特性、横风对交会气动特性的影响,以及列车几何模型的简化对交会压力波和气动特性数值模拟结果的影响。研究表明：列车-轨道模型的简化方法和简化程度对列车交会压力波和气动力特性曲线的影响程度与车辆的位置和有无横风等条件有关,车体的离地高度、转向架等对计算结果均有较为明显的影响。列车在无风环境中交会时,速度越大,峰值越高、波幅越大。波幅与交会侧间距和列车边界层厚度以及离地高度有关,交会侧间距的影响作用更大,间距越小,波幅越大。Steinheur给出的波幅计算经验公式仅考虑了从车肩开始的列车边界层,本文则还考虑头车流线体曲面边界层的影响,提出了一组新的压力波波幅计算公式。列车在横风中交会时,其压力波和气动力的特性曲线与无风环境中的相似,压力波波幅比无横风时的大,并随交会距离的增加而明显增加；各节车辆的气动力及其波动幅值均随交会速度的增大而增大。横风使压力波波幅、各节车辆的气动力和力矩的峰值和波幅均增大。4、通过多体动力学仿真研究了横风风速和车速对高速列车轮轨动力学性能的影响。结果表明：横风和车速对头车的脱轨系数和轮重减载率的影响最大,头车的脱轨系数和减载率在三节车中最大；头车背风侧的脱轨系数最大值和头车迎风侧的减载率最大值均随着风速的增加而明显增大：同时,动力学性能参数随编组车辆数量的增加而逐渐增大。对于CRH型高速列车,若采用京津线轨道谱,以脱轨系数作为安全性评价标准即可；若采用德国轨道谱,则还需要补充轮重减载率作为安全判据。此外,本文实现了加载随机气动荷载进行动力学仿真。5、研究了横风作用下的高速列车安全控制方法。基于空气动力学和轮轨动力学分析了列车在不同横风风速作用下的运行速度安全域即列车限速运行问题,给出了相应风速下的列车速度阂值；设计了一种双层腔室结构的新型透风式挡风装置,对其挡风作用和自身抗风性能进行了模拟分析,发现其具有较好的综合性能。同时,提出了利用抽吸气法控制边界层分离以减小列车的横风气动荷载的横风主动控制新方法,并分析和论证了其作用原理和效果,为提高列车的横风安全性提供了一种新的思路和方法。更多还原

【Abstract】 High-speed train is of complicated shape and high slenderness ratio, it causes three dimensional viscous flow that is complex and strongly nonlinear. When high-speed train runs in crosswind, the flow field and aerodynamic performance will change, as well as wheel-rail dynamic performance, thus influenting the safety of high-speed train on operation. There has been a substantial amount of research carried out to investigate the effects of crosswind on high-speed train and the aerodynamic safety in different parts of the world at present, while in the fields of complicated scene modeling, crosswind aerodynamic analysis, crosswind unsteady properties, and the influence of crosswind aerodynamics on safety of running train, remain to further investigation.Based on method of combining theoretic analysis, model test, flow numerical simulation and multi-body dynamics simulation, issues of crosswind aerodynamics of train and the relevant track dynamics were numerical simulated and analyzed by taking CRH high-speed train as the research object, and issues of train safety control in crosswind were studied. The main contents include the following parts:1. Aerodynamic performance of single car in open air and cross wind was studied. The results show that the different value of aerodynamic force between simulation with uniform wind and that with lower atmospheric boundary layer wind, is20%-60%, and the value is relative to road conditions such as flatland, embankment and bridge, as well as the location of train. So there is obvious deviation from the actual situation when estimating train safety in crosswind with uniform wind. The influence law of aerodynamic characteristics affected by cross winds speed, wind direction and driving speed is described by cubic polynomial function, and the influence on head train is the most obvious. The relationship between aerodynamic drag coefficient, wind speed and wind direction can be described by dimensionless comprehensive formulae; for different train consists, aerodynamic performances of head train are almost same, so for the head car of a train that consists of more than three cars, the aerodynamic safety can be estimated in a certain extent, based on the analyses on a train that consists of three cars. The aerodynamic loads of pantographs and bogie account for10～20%of each train, so it should not be ignored;2. Flow field around high-speed train and transient behavior of the aerodynamic characteristics in constant wind field were simulated by Detached Eddy Simulation, and the unsteady property was analyzed. The results show that, in steady inlet flow field, there are separated vortexes with different intensities and geometric dimensions that change and pulse randomly with time on the leeward side and wake region of train; the time-averaged value of unsteady aerodynamic load value of each car is almost the same with that calculated in whole-field steady flow, while the peak value of transient load is higher than the time-averaged value; the maximum peak values of amplitude frequency spectrum and power spectrum are not same, but they are concentrated in0-4Hz, which is in the range of inherent frequency of some train parts. For head car, the range of distribution frequency of lateral force and overturning moment is large, it has a wide range of frequency coupling with the train itself, and the aerodynamic safety is poor in crosswind. The frequency that corresponded to maximum peak values of power spectrum of aerodynamic load on bogies are different, but they are concentrated in0.5～3.5Hz.3. The aerodynamic performance of high-speed train passing by in open air, the influence of crosswind on aerodynamic performance of meeting trains, and the influence of simplification of train model on the result of meeting trains simulation were analyzed based on moving mesh. The results show that for meeting trains at same speed, pressure pulse is basically proportional to the speed; for meeting trains at different speed, pressure pulse is effected by the ratio between the two speed, pressure pulse of lower speed train is higher than that of higher speed train; for passing trains in crosswind, pressure pulse is higher than that without crosswind, and pressure of every point on the leeward side is higher than that on the upwind, crosswind increases the danger of trains passing by, but the danger level of leeward train and upwind train are different. Aerodynamic performances of trains passing by in different road conditions were compared. Pressure wave and aerodynamic coefficient of meeting trains simulated with real model are higher than that with simplified model. In conditions of crosswind and non-crosswind, there were greater differences in pressure wave and aerodynamic force coefficient of meeting trains simulated with simplified model and real model, the difference of pressure wave amplitude can be one time higher, and the difference of aerodynamic force coefficient can be3～4times higher, and generally that with real model is higher.4. Influence of crosswind velocity and driving velocity on wheel-rail dynamic performance of high-speed train was studied based on multi-body dynamics simulation. The results show that crosswind and driving velocity are most influential parameters on derailment coefficient and wheel load reduction rate of head car, and the derailment coefficient and reduction rate of wheel load of head car are the largest among the three cars; the maximum values of derailment coefficient on the leeward side of head car and wheel load reduction rate on the windward side of head car increase obviously with the increase of wind velocity; and these dynamic performance parameter values increase with the increasing number of cars that compose a train. For the CRH high-speed train, derailment coefficient is only needed as safety evaluation criterion when track spectrum of Beijing-Tianjin railway line is employed; while wheel unloading rate should be added for safety evaluation criteria when track spectrum of German railways is employed. In addition, increasing random aerodynamic load in simulation was realized in the research.5. Safety control method of high-speed train in crosswind was studied. Security domain for train of running speed at different crosswind speed, namely speed limit of running train, was analyzed based on aerodynamics and wheel-rail dynamics, and the limited train speed was given; a new wind-proof device that ventilated with double-layer chamber was designed, and it is proofed of good comprehensive properties by simulating and analyzing the ability of keeping out the wind and wind self-resistance. Meanwhile, A new active-control method in which boundary layer separation is controlled through suction to decrease crosswind aerodynamic load on train is proposed, the action principle and effect were analyzed and proofed, which is a new way provided to improve crosswind safety of train.更多还原