列车空气动力学数值仿真研究

第23卷,第4期中国铁道科学2002年8月CHINA RAILWAY SCIENCEAugust, 2002文章编号:1001-4632(2002)04013207博士论文摘要列车空气动力学数值仿真研究武青海铁道科学研究院机辆所,北京100081)关键词:列车空气动力学;有限体积法;湍流模型;磁悬浮列车中图分类号:U260.111:V211.3文献标识码:A限差分法、有限单元法和有限体积法)1前言对于列车空气动力学,与传统的试验研究方法相比数值仿真技术方法可以随时随意给定所需参数自从20世纪60年代,日本建成时速达210km进行仿真计算,并利用计算结果选择最佳设计,从的东海道新干线以来,世界铁路的高速化技术得到而节省人力、物力、财力,缩短产品设计周期。还迅速发展,使得铁路运输在经济发展中再次发挥了有工程中遇到的反问题,诸如要求预先给定流动结重要作用。2001年,法国建成了运营速度达300km果,然后通过计算来确定物面形状,而这些都是试h-的地中海线,将世界铁路的高速化进程又推向验所无法做到的。可以说,对于解决工程问题,仿个新的高潮。真计算可以帮助选型,减少设计费用,缩短设计周随运行速度提高,空气阻力等列车空气动力学期。并且对于某些特殊问题,仿真计算还可以代替问题日益受到重视。因此为实现高速铁路的安全、试验。因此本文采用了数值仿真方法来研究列车空舒适、降低能耗并满足环境保护的要求,世界各国气动力学问题。逐渐开展了对列车空气动力学问题的研究,并在此这其中有限体积法在列车空气动力学数值仿真基础上形成了一个独立的学科——列车空气动力研究中有着其它计算方法无法比拟的优势,并且也学是计算流体力学中目前最为流行的计算方法,因此列车空气动力学问题可以分为以下几类:空气本文采用了有限体积法进行列车空气动力学数值仿阻力;侧向风的空气动力学特性;会车时作用在列真计算。车上的气动压力;列车风;隧道内的压力波动;隧道出口微气压波;车体表面湍流边界层的压力变3理论基础及数值计算方法动我国在此方面的研究起步较晚,90年代初才正列车是一个长宽比很大的细长物体,形状比较式开始,起初主要是进行实车试验及风洞试验;数复杂,而且近地运动,所以绕列车的空气流动是完值仿真技术尽管与世界先进水平相差很大,但近几全三维的流动。在列车尾部会出现一对很强的尾年发展速度也很迅速涡。通过列车外部流场的基本特征以及流场雷诺数来判断其流动的形态,可以知道列车外流场为湍流2列车空气动力学主要研究方法流场I凵中国煤化工论研究及实际应用中试验研究方法(风洞试验、水洞试验、电模拟都已CNMHG校满意的结果特别是试验实车试验)和数值仿真研究方法(面元法、有对外部流动的研究较多。因此本文选用kε双方程湍收稿日期:200205作者简介方据"3-),男,河南安阳人,博士第4期博士论文摘要133流模型来研究列车空气动力学问题。△y23G,△xYH2k-ε双方程湍流模型的求解方程组由以下基本Re△y2ayRe1△z方程组成连续方程变换后得到最终形式dU dF dg dHdFdG雷诺方程H△d2+(△xm△ym△zm…)0+pax,=p、少当a3,y分别取值小于或远小于m时所采用的网格和差分格式才能比较正确地计入各方向的粘性贡献。因此在α3,γ分别取值m时就可以得到dx: a湍动能k方程临界网格间距值Δx*、Δy*、△z*。Ig hIgErak, duiau'. dg△z=gRe湍流耗散率ε方程5计算域的选取2u dump在仿真计算中,一般采取有限计算域来代替无2限计算域,计算域的大小直接影响到计算结果的可dx dx: d信程度。但是对于不同类型计算对象,其计算域的ut;/u’;du’;du大小不能一概而论,所以需要具体问题具体对待。ax. ax adx: d本论文中的计算域的选取采取了试算分析的方法确au';o’oua-u'定。在对于计算域的选取中,试算方法不失为一种有效的方法数值计算方法采用有限体积法中常用的SIPE( Semi-Implicit Method for Pressure-Linked Equa6移动网格技术ions)求解离散方程组。在列车交会和过隧道的瞬态计算中,存在计算4贴体网格间距的确定对象之间的相对运动,利用移动网格来模拟物体之间的相对运动,可以很好地进行处理移动网格界面三维流动无量纲化的NS方程之间的边界条件。dU dF aG dH在移动网格的一些实际应用中,计算域的大F dG aH在计算过程中有很大变化,此时在瞬态计算中可通Rell axt ay过单元移除或添加来解决上述问题,以保证计算域阶精度的差分格式求解后,方程成为的完整性。dU, aF(dFr aGat t ax tRe7以 STARCD为基础的仿真程序dHd2/+△xm△ym△m灬…)中国煤化工CNMHG件作为核心进行列车a grewIg re外部流功计算,世一个用软件应用于具体专业时方程经需要与其他程序一起使用以及进行必要的二次开发才能更好地为本专业服务aU3 F aG dH△xdF2o方方数据y+z=Re△xx+134国铁道科学第23卷开始型列车头尾的压力差,且前者的高压区受力区域面给定列车模型主要外形尺寸参积要大于后者,因此钝头型列车的头尾压差阻力比流线型列车的头尾压差阻力大得多在CAD图形软件中建立列车模型的主要截面数据(4)钝头型列车总的运行空气阻力要大于流线通过DF格式转换,进入UCAD程序建立三维列车模型型列车的空气阻力。要降低列车的运行空气阻力,输出列车模型表面特征数据,生成格式转换文件须从优化设计列车头尾形状入手,好的流线型列车形状是降低阻力的主要有效手段进入 STARCD前处理程序将计算域合理分成若干子域,然后划分计算网格10列车风计算结果进入 STARCD后处理程序采用数值仿真方法计算分析了流线型和钝头型云图,编制程序从 STARCD中两类车体周围列车风基本特征(1)以神州号动车组为代表的流线型车体周围编制列车空气动力性能结果数据处理程序列车风基本特征:列车风合速度在车头车尾各出现通过绘制图表程序生成图表个峰值,随距地面高度增加,尾部波动要大于头结束部的波动;车头附近压力场出现一个由正到负的压经过上述这样对ARCD软件的修正以及二次力波,且最大正压力出现在车头的前方;车尾附近开发后,可以让工程设计人员很方便地应用该软件有一个由负到正的压力波,波峰出现在列车尾端的进行产品的前期开发和研究后方。(2)以Ss8列车编组为代表的钝头型车体周围8计算模型选取与简化列车风基本特征:列车风合速度在头部的波动要远大于尾部的波动;压力场的分布规律也验证了这为不失一般性,与实际情况相结合,选取了六点,说明头部扰动产生的危险程度要大于尾部。种车型:DF4D,DF11,SS8,神州号,蓝箭号,270通过分析列车风速度场研究分析,为确定我国kmh电动车组铁路沿线安全距离提供了理论和科学依据。计算模型建立应遵循两条原则物理的真实性、数学计算的可行性11列车过隧道和交会时的数值伤真就以下几方面对列车模型进行简化:结果采用两动一拖模拟列车编组、简化列车表面、简化车体底部等。1)采用简化模型分析了列车进入隧道到出隧道期间列车车身上的压力变化和隧道内的压力波9列车外部流场计算结果动特征。若计算机工作能力许可,经精确计算,可为隧道净空面积和横截面形状设计时的空气动力学(1)对270kmh-电动车组在横风工况下的题提供参考依据风洞试验结果与仿真计算结果进行了比较,两者吻(2)初步探讨了列车交会时,两列车内侧车身合很好,说明采用 STARCD软件能够较好地描述和侧壁承受了车头车尾通过时的两次压力瞬变,但是研究铁路列车空气动力学性能。分析了六个模型车对于两车之间流场复杂的流动杋理尚未有定论。身纵向对称面上的压力分布规律,从而可以定量比较流线型列车与钝头型列车的区别。12(2)运营速度在120kmh-1-160kmh-1范围研究H中国煤化工动力学数值仿真CNMHG内的列车,若采用流线型车体,则与普通列车相比,可以使空气阻力降低70%以上,从而达到降低〔1)对流场而言,不外包形状的磁悬浮列车能耗的目的外部流场比外包形状的要复杂,阻力系数也有所增3)钝灰殒车车头与车尾的压力差大于流线大,所以流线型的外包形状比较有利于列车周围气第4期博士论文摘要135体的流动。但磁悬浮列车与线路是否外包对总旳运(3)高速铁路隧道断面形状及岀入口形状的研行空气阻力的影响不大。究(2)在对列车模型简化的基础上,磁悬浮列车4)隧道内部通风以及散热等问题的运行空气阻力计算结果比轮轨式列车大13%左5)列车交会时两列车中间区域流场的空气流右。因此,相同头型和迎风截面外形的轮轨式列车动机理研究以及线间距的确定的运行空气阻力要小于磁悬浮列车。(6)气动噪声问题13工作展望希望通过对列车空气动力学的数值仿真研究,能够建立“数值风洞”,使其在工程设计中得到广(1)底部转向架的近似模拟泛应用,加速发展我国的高速铁路技术。(2)车内通风问题a Study on Numerical Simulation of Train Aerodynamicswu Qing-HaiChina Academy of Railway Sciences, Beijing 100081, Chinasure shift in tunnel the micro-pressure at tunnel exit, and1 Introductionthe pressure shift in the turbulence layer of train surfaceThis study in China is behind the world, startedAfter the first Shinkansen train in Japan run success- from actual train test and wind tunnel test at the early dayfully at 210 knt h-I in 1 960 s, the high-speed railway of 1990 s. Recently the numerical simulation techniquetechnique has been developed quickly all over the world has been developed rapidly although there is a big distanceand made railway transportation play a important role in e- between China and the worldconomic development again. In 2001, the Med Line wasbuilt in France so the high-speed technique of the world 2 Main study methods for train aerody-railway had reached a new steWith raising the train running speed, train aero-dynamIcsnamics problems have been regarded increasingly. Thestudy on train aerodynamics problems have been developedTest study method( wind tunnel test, water tunneltest electronic simulation test and actual train test ), andand comfortable of high-speed train reduce the powers numerical simulation method panel method, finite differconsume, and environmental protection. And based on encethese an independent subject, train aerodynamics has metheH中国煤化工 ethod and finite volCNMHGappearedFor train aerodynamics, compared with traditionalThe train aerodynamics can be classified as belotest study method, the simulation calculation can be madeAir drag side direction wind the air pressure on at any time when setting the required parameters. Thethe train wheh erosing, train induced airflow, the pres- best design will be selected according to the result, and it136国铁道科学第23卷an cut down the consumption in manpower money andlL:antage of simulation method can be showed also throughTurbulence kinetic energy h equationthe anti-question in project. Such as the flow result areknown in advance then the surface shape of product willbe confirmed by calculation, while the target can not be2reached by test method. That is to say, for project probTurbulence dissipation rate E equationlems the shape can be selected, the design expense canbe reduced and the design period can be shortened alsojdx, dthrough simulation calculation And it can substitute fortest in some special problems. So the numerical simulationa∈)-2t'ujaxmethod is used to research the train aerodynamics proldu;/du’;o7u't0lems in this paperdCompared with other calculation methods the finitedu';du';Ou’volume method( FVM) has more advantage in train aerodxr dx: d.dynamics research. And it is one of the most popular calThe numerical calculation method adopts SIMPLEculation methods in CFD today. Therefore we adopt FVM( Semi-Implicit Method for Pressure-Linked Equations )ofto make the numerical simulation calculation for train FVM to solve the discredited equation setaerodynamIcs3 Theory foundation and numerical calcu- meshes near walllation method3D zero dimension N-S equationdU dF dG dHTrain has a slender body with large ratio of length towidth and complicated shape. And train runs close to thedF. dG. dHground. So the airflow around train is 3D completely. ARe, ox+ apair of strong tail vortex appears behind train. AccordinAfter m rank precision difference form solution,eto the basic characteristic of the airflow around train and quation becomesthe flow reynolds number we can know that the flow fieldau dF aG dH 1 dF aGaz Rearound train is a turbulence fieldIn theory research and application k-E turbulencea2)+△rAym△”灬)model has reached a mature degree and gotten many morelureIg Resatisfied results especially for exterior flow field. So weadopt the k-e turbulence model to study the train aerodSubstitute in the above equation and rearrangeU dF dg aH△xdF2The solution equation set of h-E turbulence modelRe1△xax+consists of the following aquatic△y2dG,△zH中国煤化工02+Continuity equationHCNMHGWe get the final expression1+3F+3+dFGa片数据a- op△z+O△xAym△znr…)第4期博士论文摘要137When a,B and y are less than m or more respectivelthe adopted mesh and difference form can include the viof traincosity contribution of each direction correctlyTherefore as a,B and are equal to m we canEstablish the main section data of train model in CAD softwareget the critical distance between meshes Ax,AyEstablish 3D train model in UGCAD by format transformOutput the surface data of train model,grelg reand create transform file withnto sTaRCd preprocedurelIgErColculation field divided into some sub-fields and5 Selection for the calculation fieldInto STARCDIn the simulation calculation people substitute theOutput flow field and pdistribution graphlimited calculation field for the infinite calculation field ingotten the result dataprogrammMinGgeneral. The size of the calculation field influences theDesign program to treat with the result data of train aerodynamicscreditable degree of calculation result directly. But for thedifferent type models their calculation field cannot beChart generated by prconsidered similarly. So specific problem should be treated especially. The calculation fields in thAfter above secondary development project plannerfirmed by the pilot calculation method. The pilot calculacan use STARCD software easily to make prophase develtionthod may be aneffective way for the calculation opment and research for productfield selection8 Selection and simplification of calcula-6 Sliding mesh techniquetion modelIn order to ensure generality six type trains are seIn the transient calculation of train crossing and trainlected: DF4D, DF11, S$8, Shenzhou, Lanjian 270 kmpassing a tunnel there is a relative movement between thehpower callculation objects. It can deal with the bounThe calculation model's establishment should followtion between the movement mesh interfaces nicely thoughIn some applications of sliding mesh, the size of cal- mathematical calculatio ity of physics and feasibility ofthe relative movement simulated by sliding meshculation field may change largely at the calculation proThe train models are simplified at the followincess. At this time we can use cell removal and addition topects according the principles: two power cars and onesolve the above problem, in order to ensure the integrality trail car used to simulate train set simplification of trainof calculation fieldsurface and the train body bottom9 The calculation result of train exterior7 Simulation program based onflow fieldSTARCD(1) After comparison, the calculation results of 270The calculation for the exterior flow around train is km.YH中国煤化工 condition of crosswind fitmade where the fluid software staRCd is considered as withC Gnel very well. It meansthe core. When general software is used to certain field, the software STARCD can describe and study the trainit should be used with other programs together or made aerodynamics betterecondary development in order to serve best for this spe-(2) For train which run at 120 kml h- -160 kth-, if a streamline body is adopted its air drag will be138中国铁道科学第23卷less 70 than that of train with general body in order to passing tunnel and the pressure fluctuation in tunnel is anreach the target reducing power's consumeeIs. The study will provide ref-(3)The pressure differences of nose for blunt nose erence basement for the aerodynamics problems during detrain are larger than that of streamline train and the same signing tunnel area and section shape by accurate calculaas the end. The high-pressure size of the former is larger tion if the work ability of computer allowsthan that of the latter also. So the pressure differences be-(2) The sidewall of train body between two trainstween nose and end of blunt nose train is larger than that endures the pressure transient twice during trainf streamline trainBut the complicated flow mechanism between two trains is(4) The total running air drag of blunt nose train is not yet clear up to nowger than that of streamline train In order to reduce the12 Numerical simulation study of maglevgood streamline shape is main effective way to reduce airaerodynamIcs(1) For the flow field, no wrap maglev is compli-10 The calculation result of train inducedcated correspondingly compared with wrap maglev its airdrag coefficient is much larger thanof wraairflowSo the maglev with streamline wrap shape is propitious toThe basic characteristic of train induced airflow is the air flow around train but it has small influence foranalyzed with numerical simulation methodtotal air drag whether the shape between maglev and rail(1)The basic characteristic of train induced airflowaround the streamline train represented by Shenzhouhao(2)Based on the simplified model the calculationpower car set: the peak value of the resultant velocity Vxy result of maglev air drag is more than that of wheel trainappears twice at the nose and end respectively. The Vay about 13 percent. Therefore the air drag of wheel train isshift of the end is larger than that of the nose when the less than that of maglev with the same nose type and winddistances to grourise gradually. One press wave froward sectonpositive to negative appears near the train nose and themost pressure lies in front of train. Another press wave13 Work prospectfrom negative to positive appears near the train end and(1) Approximate simulation for the train bogiethe peak lies behind the train end(2) Ventilation problem inside train(2)The basic characteristic of train induced airflow(3) Study on the section shape entrance and exitaround the blunt train represented by SS8: The fluctuation shape of high-speed railway tunnelof the resultant velocity Iter than(4) Ventilation and heat emission in tunnelthat at the train end. The distribution law of pressure field(5) Study on the air flow mechanism duringalidates this point also. That is to say that the danger de- crossing and the interval between linesgree made by the nose fluctuation is larger than made by(6)Air noise problemthe train endset upBy analyzing the train-induced airflow this paper through studying train aerodynamics. Our high-speed railprovides theoretical and scientific basement for the railway way technique can be developed fast with the applicationsafety distance in China11 The simulation result of train passing KeyI Vpnd tunnel" widely in engineering design中国煤化工FVM TurbuleCNMHtunnel and crossingmoc责任编辑刘卫华)(1) The pressure change on train body during train