国内高速列车气动噪声研究进展概述

随着运行速度的提升,气动噪声逐渐成为高速列车最主要的噪声源,并极有可能成为新设计高速列车的一个技术瓶颈。开展高速列车气动噪声研究,明晰高速列车气动噪声机理与规律,发展低噪声高速列车外形设计对更高速度级的高速列车研发具有重要意义。本文主要对自2010年以来国内进行的高速列车气动噪声研究进行梳理总结。首先详细介绍了高速列车气动噪声研究采用的一系列方法,主要从实车试验、风洞实验以及数值模拟方法三个方面展开。在掌握高速列车气动噪声研究方法的基础上,进而探讨了当前高速列车气动噪声研究的现状,重点就高速列车气动噪声源识别、主要噪声源机理与特性、噪声源优化等方向进行了阐述,并明确了当前研究获得的一些主要结论。最后简要探讨了高速列车气动噪声未来可能的研究方向

典型路基结构对高速列车横风气动特性影响分析

由于地域及环境的限制, 高速铁路采用多种路基结构如平直地面、不同高度路堤、高架桥等,当列车运行在路堤及高架桥上时,车体周围的绕流流场比平直地面更加复杂。在强横风的作用下,不同的路基结构上的高速列车横风气动特性存在明显差异,不合理的路基结构将影响列车的横风安全性。同时列车结构复杂,转向架、受电弓等都对列车的流场特性有重要作用,过于简化的短编组列车外形不能够精细反映列车的真实气动特性。为研究典型路基结构对高速列车横风气动特性的影响,以9编组动力集中型高速列车实车为研究对象,考虑风挡、转向架、受电弓等细节特征,对列车运行速度为200 km/h,横风速度分别为20 m/s、30 m/s、35 m/s、40 m/s,路基结构分别为平直地面、3 m路堤、6 m路堤、高架桥等四种场景下的高速列车空气动力学性能进行了仿真计算和对比,分析了不同路基地面条件下列车的横风气动特性的差异及规律,为横风条件下复杂路基结构的列车运行安全控制提供了参考

Study on Outdoor Aerodynamic Noise and Interior Noise Characteristics under Aerodynamic Excitation of High Speed Train

在当前高速铁路和高速列车发展方面，&ldquo;十四五&rdquo;规划提出打造&ldquo;交通强国&rdquo;，构建&ldquo;智能交通&rdquo;等新远景目标，提出推进CR450高速度等级中国标准动车组、谱系化中国标准地铁列车。可以预见，在高速列车未来设计中，在气动方面将会面临气动阻力和气动噪声增加的问题，而对于列车运行，希望能耗越低越好，同时噪声方面必须满足一定的规范标准。因而，减阻和降噪不可避免成为更高速度级高速列车外形设计的两个关键指标。目前，国内外学者在高速列车气动特性和噪声特性方面都有相关研究，但在列车减阻和降噪上还有很大的探索空间，兼顾减阻和降噪对列车问题的系统性研究工作不足。具体来说，在室外气动噪声的探究上，大多局限于对远场特定监测点噪声情况进行探究，对减噪方面的关注不足；在室内噪声上，目前普遍采用的室内噪声分析方法中，声学有限元方法局限于低频段区，能量法常用于对高频噪声进行分析，但分析的准确性不足。在本文的分析中，对高速列车关键噪声源诱发的外场噪声特性进行了研究，识别出关键声源，并通过构形设计进行了外场减阻降噪研究；在对气动激励引起的内部噪声上，运用振动声传递向量法对高速列车在不同玻璃设计下的传递特性进行了分析，并分析了气动激励下车内不同位置噪声频谱特性以及不同构型设计对内场噪声的影响。具体来说，本文研究主要包括以下内容： （1）分析高速列车减阻和降噪的极限范围，并对列车各阻力源和噪声源进行分析，量化其对整车阻力和整车噪声的贡献。探讨列车头型长短和横截面积对列车阻力和噪声的影响。对比高速列车上头车、中车、尾车、受电弓、转向架的阻力和噪声贡献。分析各部件诱发噪声在不同监测点上的频谱特性，分析不同部件在不同频率对不同位置监测点噪声的贡献。室外噪声的求解上还探索了叠加求解高速列车室外噪声的方法，并对其计算可靠性进行验证。 （2）以各部件对阻力和噪声的贡献为基础对局部部件进行构型设计，实现减阻并分析其对噪声的影响。主要针对高速列车上具有代表性的，影响较为明显的受电弓和转向架两大关键部件进行构型设计，并对不同构型方案进行气动力和气动噪声的详细分析，优选出良好的设计方案。 （3）将振动声传递向量法（VATV）运用于气动激励下高速列车室内噪声的快速计算。将VATV方法与直接声振耦合法求解室内噪声进行了对比，验证了该方法在求解室内噪声上可靠性。研究了列车上安装不同设计参数玻璃对气动激励源的传递特性。在室内噪声分析上，还分析了对室外噪声影响较大的受电弓和转向架对室内噪声的影响，也对构型优化设计方案对室内噪声的影响进行了对比分析。 总体说来，本文的目标在于探讨关键部件对气动阻力以及室外和室内噪声的影响，实现减阻的同时兼顾降噪。总体上通过对高速列车重要的气动阻力源和噪声源部件，如：转向架舱、裙板、受电弓、头型进行不同结构设计以实现目标。在具体的分析步骤上，本文对高速列车室外气动噪声特性进行分析，初步判断关键噪声源，通过声学有限元计算并结合噪声叠加的思路得到室外气动噪声特性；然后将气动激励源局部或整体加载到列车上，进一步得到室内噪声特性。该研究思路有利于降低计算量，更清晰的分析得到任意噪声源的贡献特性，得到室内噪声总体分布情况，对于列车减阻降噪具有参考意义。</p

高速列车受电弓气动噪声特性分析

以某高速列车受电弓为研究对象,探讨其在350km/h速度下的气动噪声特性。采用延迟脱体涡模拟(DDES)和声学有限元(FEM)相结合的方法,分析带导流罩受电弓在升起和下降状态下,近场和远场气动噪声空间分布规律和频谱特性,研究流场计算时不同建模方式对诱发噪声幅值和指向性的影响以及壁板的反射和散射作用对噪声频谱特性的影响。结果表明:1)在本文选取的受电弓外形和开口方向下,降弓和导流罩诱发噪声略大于升弓和导流罩诱发噪声;2)导流罩在低于300Hz的低频区诱发噪声比例较大,而受电弓在300Hz后诱发噪声影响较大;导流罩诱发噪声在升弓情形时所占比例相对较大;3)在指向性上,导流罩诱发噪声在受电弓前部贡献较大,受电弓诱发噪声在后部区域贡献较大;在列车正上方区域,弓体诱发噪声大于导流罩诱发噪声,是主要的气动噪声源

Numerical study on unsteady wake characteristics of an urban maglev train

As the running speed increases, the aerodynamic loads become dominant for high-speed ground vehicles. Meanwhile, the aerodynamic lift of the trailing car becomes crucial at higher speed, which may lead to security and comfort problems. Flow field details are the root to the aerodynamic loads. Study on the wake characteristics of the train could shed light to learn the mechanism of their aerodynamic loads and know how to improve their aerodynamic performance. In the present paper, the urban maglev train with a design speed of 200 km/h is mainly focused on. Numerical investigation is adopted for current study. The Improved Delayed Detached Eddy Simulation (IDDES) numerical approach is utilized to count for unsteady flow details. To characterize the vortex structures, the iso-surface of Q for urban maglev train is obtained and compared. Due to the existence of guide way, the streamline of maglev trains is much more influenced by the guide way. The ground effect for maglev trains is more obvious. The streamlined shape is quite essential to the flow phenomena, and as a result, the vortex structures for urban maglev trains are also different. Guide way could lead to more vortices, which is common for maglev trains. However, lateral vortex could be observed for urban maglev trains, which is unique and is a result of the flat shape of the trailing nose. Meanwhile, the slipstream in the wake of the train is also compared. The streamlined shape of urban maglev trains is the bluntest, which induces the relatively biggest train wind. Based on the above analysis, the unsteady characteristics of flow field for urban maglev train are obtained and the main vortex structures are characterized. Based on the unsteady analysis of flow field, the relationships between aerodynamic loads of the trailing car and different kinds of trailing vortices are obtained. Current study could shed light on the understanding of mechanism of aerodynamic performance of a train and how to design the streamlined shape for trains with certain operational speed. Copyright © 2019 ASME

Analysis of Aerodynamic Noise Characteristics of High-Speed Train Pantograph with Different Installation Bases

The high-speed-train pantograph is a complex structure that consists of different rod-shaped and rectangular surfaces. Flow phenomena around the pantograph are complicated and can cause a large proportion of aerodynamic noise, which is one of the main aerodynamic noise sources of a high-speed train. Therefore, better understanding of aerodynamic noise characteristics is needed. In this study, the large eddy simulation (LES) coupled with the acoustic finite element method (FEM) is applied to analyze aerodynamic noise characteristics of a high-speed train with a pantograph installed on different configurations of the roof base, i.e. flush and sunken surfaces. Numerical results are presented in terms of acoustic pressure spectra and distributions of aerodynamic noise in near-field and far-field regions under up- and down-pantograph as well as flushed and sunken pantograph base conditions. The results show that the pantograph with the sunken base configuration provides better aerodynamic noise performances when compared to that with the flush base configuration. The noise induced by the down-pantograph is higher than that by the up-pantograph under the same condition under the pantograph shape and opening direction selected in this paper. The results also indicate that, in general, the directivity of the noise induced by the down-pantograph with sunken base configuration is slighter than that with the flush configuration. However, for the up-pantograph, the directivity is close to each other in Y-Z or X-Z plane whether it is under flush or sunken roof base condition. However, the sunken installation is still conducive to the noise environment on both sides of the track.</p

大Reynolds数液滴Marangoni迁移的空间实验装置

讨论了液滴热毛细迁移的空间实验装置，该实验是中国神舟号飞船中的一个项目。与国际上同类装置比较，它具有不需要宇航员直接操作，领先程序自动控制及遥科学手段完成全部科学实验的能力。它不仅能完成大Reynolds数的液滴迁移实验，而且在这类空间装置上使用了等厚型光学干涉系统

Aerodynamic optimization using passive control devices near the bogie cabin of high-speed trains

Bogies are responsible for a significant amount of aerodynamic resistance and noise, both of which negatively affect high-speed train performance and passenger comfort. In the present study, the passive control method is applied in designing the bogie cabins of a high-speed train to improve its aerodynamic characteristics. Two passive control measures are introduced, namely, adding a spoiler and creating diversion grooves near the bogie cabins. Furthermore, the aerodynamic and aeroacoustic characteristics of a high-speed train operating at 350 km/h under different control strategies are numerically investigated using the improved-delayed-detached-eddy simulation (IDDES) and the acoustic finite element method (FEM). The impacts of passive control devices on drag reduction, slipstream, and aerodynamic noise are presented and discussed. Numerical results reveal that the passive control devices have a major effect on the slipstream around the train. The amplitude of the fluctuating pressure is higher in the first half of the train than in the second half The first bogie has the maximum amplitude of the acoustic pressure for both the train with and without passive devices. In the far field, the spoiler installation and placement of the diversion grooves in the front of the bogie cabin can significantly reduce aerodynamic drag and noise. Hence, as shown in this study, using passive control methods to improve the aerodynamic and aeroacoustic properties of high-speed trains can be a viable option

Numerical Investigation on the Influence of the Streamlined Structures of the High-Speed Train's Nose on Aerodynamic Performances

The structural design of the streamlined shape is the basis for high-speed train aerodynamic design. With use of the delayed detached-eddy simulation (DDES) method, the influence of four different structural types of the streamlined shape on aerodynamic performance and flow mechanism was investigated. These four designs were chosen elaborately, including a double-arch ellipsoid shape, a single-arch ellipsoid shape, a spindle shape with a front cowcatcher and a double-arch wide-flat shape. Two different running scenes, trains running in the open air or in crosswind conditions, were considered. Results reveal that when dealing with drag reduction of the whole train running in the open air, it needs to take into account how air resistance is distributed on both noses and then deal with them both rather than adjust only the head or the tail. An asymmetrical design is feasible with the head being a single-arch ellipsoid and the tail being a spindle with a front cowcatcher to achieve the minimum drag reduction. The single-arch ellipsoid design on both noses could aid in moderating the transverse amplitude of the side force on the tail resulting from the asymmetrical vortex structures in the flow field behind the tail. When crosswind is considered, the pressure distribution on the train surface becomes more disturbed, resulting in the increase of the side force and lift. The current study reveals that the double-arch wide-flat streamlined design helps to alleviate the side force and lift on both noses. The magnitude of side force on the head is 10 times as large as that on the tail while the lift on the head is slightly above that on the tail. Change of positions where flow separation takes place on the streamlined part is the main cause that leads to the opposite behaviors of pressure distribution on the head and on the tail. Under the influence of the ambient wind, flow separation occurs about distinct positions on the train surface and intricate vortices are generated at the leeward side, which add to the aerodynamic loads on the train in crosswind conditions. These results could help gain insight on choosing a most suitable streamlined shape under specific running conditions and acquiring a universal optimum nose shape as well.</p

高速列车气动外形优化研究进展

随着运行速度的提升,高速列车对气动外形的要求也越来越高,追求性能优异、美观大方的气动外形是新型高速列车研发的一个重要方向.基于当前高速列车外形研发的思路,可以将气动外形优化概括为基于流场机理的改型优化和基于优化算法的外形优化两类.本文简要回顾了当前国内外在这两类优化途径上的系列工作,着重介绍了作者所在团队近年来做过的一系列气动外形优化工作.在基于流场机理的改型优化上,着重从"和谐号"和"复兴号"这两款主力车型的外形研发上探讨其改型优化的思路,主要探讨了空调导流罩、受电弓平台、风挡和转向架裙板几类对列车阻力影响较为明显的部件的优化设计,并介绍了其相对于上一代车型在气动性能上的提升.基于优化算法的外形优化方法,则因循气动外形优化流程,在列车外形已经具有较好性能的基础上,以高速列车头型流线型为主要优化对象,分别从高速列车参数化方法、替代模型开发以及优化算法改进三个方面进行介绍.其中,高速列车参数化方法主要介绍了局部型函数法、修正车辆造型函数法和类别/形状函数法三类;替代模型开发介绍了最优化替代模型和基于交叉验证的Kriging模型;在优化算法的改进上介绍了改进的非劣分类多目标粒子群算法和连续域混沌蚁群算法两方面的内容.基于上述三个方面介绍了气动外形优化策略在典型工程上的应用案例