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1.
With the continuous improvement of the train speed, the dynamic environment of trains turns out to be aerodynamic domination. Solving the aerodynamic problems has become one of the key factors of the high-speed train head design. Given that the aerodynamic drag is a significant factor that restrains train speed and energy conservation, reducing the aerodynamic drag is thus an important consideration of the high-speed train head design. However, the reduction of the aerodynamic drag may increase other aerodynamic forces （moments）, possibly deteriorating the operational safety of the train. The multi-objective optimization design method of the high-speed train head was proposed in this paper, and the aerodynamic drag and load reduction factor were set to be optimization objectives. The automatic multi-objective optimization design of the high-speed train head can be achieved by integrating a series of procedures into the multi-objective optimization algorithm, such as the establishment of 3D parametric model, the aerodynamic mesh generation, the calculation of the flow field around the train, and the vehicle system dynamics. The correlation between the optimization objectives and optimization variables was analyzed to obtain the most important optimization variables, and a further analysis of the nonlinear relationship between the key optimization variables and the optimization objec- tives was obtained. After optimization, the aerodynamic drag of optimized train was reduced by up to 4.15%, and the load re- duction factor was reduced by up to 1.72%. 相似文献
2.
Aerodynamic forces and dynamic performances of railway vehicles are coupled and affected by each other. On the one hand, aerodynamic forces change the displacements of a train. On the other hand, displacements affect aerodynamic forces. Based on vehicle-track coupling dynamics and aerodynamics, a numerical approach to the interaction between airflow and a high-speed train is presented in this paper. Aerodynamic forces and dynamic performances of a high-speed train subjected to crosswind were numerically simulated. Results showed that the interaction between airflow and a high-speed train has a significant influence on displacements and aerodynamic forces of the head coach. Therefore, it is necessary to consider the interaction between airflow and a high-speed train subjected to crosswind. 相似文献
3.
A 2.5D finite element approach for predicting ground vibrations generated by vertical track irregularities 总被引：1，自引：0，他引：1
Dynamic responses of track structure and wave propagation in nearby ground vibration become significant when train operates
on high speeds. A train-track-ground dynamic interaction analysis model based on the 2.5D finite element method is developed
for the prediction of ground vibrations due to vertical track irregularities. The one-quarter car model is used to represent
the train as lumped masses connected by springs. The embankment and the underlying ground are modeled by the 2.5D finite element
approach to improve the computation efficiency. The Fourier transform is applied in the direction of train’s movement to express
the wave motion with a wave-number. The one-quarter car model is coupled into the global stiffness matrix describing the track-ground
dynamic system with the displacement compatibility condition at the wheel-rail interface, including the irregularities on
the track surface. Dynamic responses of the track and ground due to train’s moving loads are obtained in the wave-number domain
by solving the governing equation, using a conventional finite element procedure. The amplitude and wavelength are identified
as two major parameters describing track irregularities. The irregularity amplitude has a direct impact on the vertical response
for low-speed trains, both for short wavelength and long wavelength irregularities. Track irregularity with shorter wavelength
can generate stronger track vibration both for low-speed and high-speed cases. For low-speed case, vibrations induced by track
irregularities dominate far field responses. For high-speed case, the wavelength of track irregularities has very little effect
on ground vibration at distances far from track center, and train’s wheel axle weights becomes dominant. 相似文献
4.
To improve the aerodynamic performance of high-speed trains (HSTs) running in the open air, a multi-objective aerodynamic optimization design method for the head shape of a HST is proposed in this paper. A parametric model of the HST was established and seven design variables of the head shape were extracted. Sample points and their exact values of optimization objectives were obtained by an optimal Latin hypercube sampling (opt. LHS) plan and computational fluid dynamic (CFD) simulations, respectively. A Kriging surrogate model was constructed based on the sample points and their optimization objectives. Taking the total aerodynamic drag force and the aerodynamic lift force of the tail coach as the optimization objectives, the multi-objective aerodynamic optimization design was performed based on a non-dominated sorting genetic algorithm-II (NSGA-II) and the Kriging model. After optimization, a series of Pareto-optimal head shapes were obtained. An optimal head shape was selected from the Pareto-optimal head shapes, and the aerodynamic performance of the HST with the optimal head shape was compared with that of the original train in conditions with and without crosswinds. Compared with the original train, the total aerodynamic drag force is reduced by 2.61% and the lift force of the tail coach is reduced by 9.90% in conditions without crosswind. Moreover, the optimal train benefits from lower fluctuations in aerodynamic loads in crosswind conditions. 相似文献
5.
罗利锦 《天津成人高等学校联合学报》2014,(8):21-24
通过对CRH高速动车组的设计特点、运用方式与运行环境的分析,阐明了高速动车组列车途中运行亟待解决的关键问题;通过对高速动车组制动系统、牵引制动特性与CTCS系统的针对性研究,制定了“定方案、抓环节、细掌握”高速动车组列车操纵的应对策略,形成了定地点、定速度、定制动方式的高速动车组列车进站前制动调速的操作模式。 相似文献
6.
With the development of high-speed train, it is considerably concerned about the aerodynamic characteristics and operation
safety issues of the high-speed train under extreme weather conditions. The aerodynamic performance of a high-speed train
under heavy rain and strong crosswind conditions are modeled using the Eulerian two-phase model in this paper. The impact
of heavy rainfall on train aerodynamics is investigated, coupling heavy rain and a strong crosswind. Results show that the
lift force, side force, and rolling moment of the train increase significantly with wind speed up to 40 m/s under a rainfall
rate of 60 mm/h. when considering the rain and wind conditions. The increases of the lift force, side force, and rolling moment
may deteriorate the train operating safety and cause the train to overturn. A quasi-static stability analysis based on the
moment balance is used to determine the limit safety speed of a train under different rain and wind levels. The results can
provide a frame of reference for the train safe operation under strong rain and crosswind conditions. 相似文献
7.
不同速度高速列车车外噪声的调查研究 总被引：1，自引：1，他引：0
Bin HE Xin-biao XIAO Qiang ZHOU Zhi-hui LI Xue-song JIN 《浙江大学学报(A卷英文版)》2014,(12):1019-1033
研究目的：基于声源识别,得出车外噪声分布特性及场点主要噪声源。创新要点：1．研究高速列车噪声源强特性及频谱特性;2．揭示不同速度下不同声源频谱变化规律;3．分析车外声场场点噪声变化规律及主要声源。研究方法：1．利用车外声源识别系统（图2）分析高速列车声源分布规律及频谱特性;2．利用声源的垂向（图10）分布研究不同声源在各频率下垂向分布规律;3．利用场点声源与速度的拟合关系（图16）研究场点主要噪声源。重要结论：1．高速列车车外噪声源主要分布在轮轨区域、受电弓和车间连接区域;2．轮轨区域噪声包括滚动噪声和气动噪声,在各频率均为最显著声源;3．在整个列车高度,轮轨滚动噪声对总噪声贡献率大于气动噪声;4．车外场点噪声主要频率为630-2500Hz,主要来自轮轨滚动噪声。 相似文献
8.
The China’s high-speed railway is experiencing a rapid growth. Its operating mileage and the number of operating trains will
exceed 45 000 km and 1500 trains by 2015, respectively. During the long range and constant high-speed operation, the high-speed
trains have extremely complex and varied work conditions. Such a situation creates a huge demand for high-speed train on-board
monitoring. In this paper, architecture for high-speed train on-board monitoring sensor network is proposed. This architecture
is designed to achieve the goals of reliable sensing, scalable data transporting, and easy management. The three design goals
are realized separately. The reliable sensing is achieved by deploying redundant sensor nodes in the same components. Then
a hierarchal transporting scheme is involved to meet the second goal. Finally, an electronic-tag based addressing method is
introduced to solve the management problem. 相似文献
9.
Jie Zhang Xin-biao Xiao Xiao-zhen Sheng Rong Fu Dan Yao Xue-song Jin 《浙江大学学报(A卷英文版)》2017,18(8):617-630
This paper presents an investigation into the characteristics of interior noise of a Chinese high-speed train under several typical conditions. Interior noises within Vehicle TC01, which can be used as a head car or an end car, and Vehicle TP03, the third car counting from TC01, are measured for the train running at speeds from 260 km/h to 385 km/h, along two types of track including a slab track and a ballast track and either on the ground surface or in a tunnel. Data analyses are performed for sound pressure overall levels, frequency, area contributions, and possible generation mechanisms, showing how they are affected by train speed, running direction, track type, and tunnel. The results show that, whether TC01 is used as head car or end car, the interior noise characteristics in the VIP cabin are mostly related to aerodynamic noise. Differences in interior noise between tracks become smaller as the train speed increases. The effect of a tunnel on the interior noise is more important for the middle coach than that for the head coach. This study can provide a basis for noise control of high-speed trains. 相似文献
10.
In order to study the unsteady aerodynamics effects in railway tunnels, the 3D Reynolds average Navier-Stokes equations of a viscous compressible fluid are solved, and the two-equation k-? model is used in the simulation of turbulence, while the dynamic grid technique is employed for moving bodies. We focus on obtaining the changing tendencies of the aerodynamic force of the train and the aerodynamic pressures on the tunnel wall and train surface, and discovering the relationship between the velocity of the train and the intensity of the micro pressure wave at the tunnel exit. It is shown that the amplitudes of the pressure changes in the tunnel and on the train surface are both approximately proportional to the square of the train speed, so are the microwave and the drag of the train. 相似文献
11.
Compared to the current eddy braking patterns using a single magnetic source, hybrid excitation rail eddy brakes have many
advantages, such as controllability, energy saving, and various operating models. Considering the large braking power consumption
of the high-speed train, a hybrid excitation rail eddy brake system, which is based on the principle of electromagnetic field,
is proposed to fulfill the needs of safety and reliability. Then the working processes of the mechanical lifting system and
electromagnetic system are demonstrated. With the electromagnetic system analyzed using the finite element method, the factors
such as speed, air gap, and exciting current have influences on the braking force and attractive force. At last, the structure
optimization of the brake system is discussed. 相似文献
12.
The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence
of sandstorm weather in north China. An Eulerian two-phase model in the computational fluid dynamic (CFD) software FLUENT,
validated with published data, was used to solve the gas-solid multiphase flow of a sandstorm around a train. The train aerodynamic
performance under different sandstorm levels and no sand conditions was then simulated. Results showed that in sandstorm weather,
the drag, lift, side forces and overturning moment increase by variable degrees. Based on a numerical analysis of aerodynamic
characteristics, an equation of train stability was also derived using the theory of moment balance from the view of dynamics.
A recommended speed limit of a train under different sandstorm levels was calculated based on the stability analysis. 相似文献
13.
The seasonal-frozen layer may have an influence on embankment motion from train-induced vibrations. Based on the field monitoring in a seasonally-frozen region of northeastern China, the effects of the frozen layer on the embankment responses to train-induced vibration were investigated in winter and summer via acceleration time histories and acceleration frequency spectrums. The results show that： （1） Compared to unfrozen soil conditions, the amplitudes of longitudinal and vertical vibrations at the points near the rail were increased, different influences of freight versus high-speed trains are the most evident. （2） With greater distance from the rail, the dominant frequency ranges of embankment with both frozen and unfrozen layers narrowed and shifted to low frequency bands. （3） The predominant frequency of embankment vibration with frozen soil layers shifted to higher frequencies with the increased train speed, although there was little change with unfrozen condition. Layer condition （frozen versus unfrozen） and distance to rail both play important roles in investigating the embankment vibration characteristics and rail transit field monitoring to improve the criterion of the rail construction in seasonally-frozen regions. 相似文献
14.
高速列车刹车片检修工艺的分析 总被引：1，自引：0，他引：1
徐汇音 《实验室研究与探索》2012,31(5):58-60,205
高速列车中的刹车片是制动系统的重要组成部分,对制动性能起着举足轻重的作用,刹车片是通过与车轮的摩擦实现制动,其材料应具有耐热性强、磨损量小、摩擦系数高、机械强度高等特点.在列车运行中刹车片的磨损严重,整修量及需求量很大.通过对刹车片的结构及运行情况的阐述,分析了刹车片的检修工艺,提出了完善刹车片的整修工艺、材料研制及改善的技术创新方向. 相似文献
15.
NomenclatureV-Relative velocity vectorV′-Absolute velocity vectorω-Relative vorticity vectorω′-Absolute vorticity vectorR-Pipe radiusa-Radius of cylinder for helical vortex filament2πl-Pitch of i mage helical vortex filamentQ-Flowrate in pipe with an arbitrary cross-sectionΓ-Circulation of each helical vortex filamentV0-Constant transferal velocity of vortex filaments along thez-axisΩ-Constant angular velocity of vortex filaments around thez-axis(a,χ1) ,(a,χ2) -Relative helical … 相似文献
16.
Suspension plasma spraying (SPS) can be utilized to manufacture finely structured coatings. In this process, liquid suspended with micro- or nano-sized solid particles is injected into a plasma jet. It involves droplet injection, solvent evaporation, and discharge, acceleration, heating, and melting of the solid particles. The high-speed and high-temperature particles finally impact on the substrate wall, to form a thin layer coating. In this study, a comprehensive numerical model was developed to simulate the dynamic behaviors of the suspension droplets and the solid particles, as well as the interactions between them and the plasma gas. The plasma gas was treated as compressible, multi-component, turbulent jet flow, using Navier-Stokes equations solved by the Eulerian method. The droplets and solid particles were treated as discrete Lagrangian entities, being tracked through the spray process. The drag force, Saffman lift force, and Brownian force were taken into account for the aerodynamic drag force, aerodynamic lift force, and random fluctuation force imposed on the particles. Spatial distributions of the micro- and nano-sized particles are given in this paper and their motion histories were observed. The key parameters of spray distribution, including particle size and axial spray distance, were also analyzed. The critical size of particle that follows well with the plasma jet was deduced for the specified operating conditions. Results show that in the downstream, the substrate influences the flow field structure and the particle characteristics. The appropriate spray distances were obtained for different micro- and nano-sized particles. 相似文献
17.
通过对磁浮列车行驶时产生的噪声进行现场测试及分析,比较了列车靠近和离开时的噪声功率谱,观察并定量计算了其谱线频率的变化,从而为声波的多普勒效应提供了有效的教学及实验方法,也可为磁浮列车或其他高速列车行驶噪声的进一步研究提供有效的测量分析方法。 相似文献
18.
气速是工程和实验研究所关注的重要参数之一,在化工领域内对流体速度进行准确测量对实验结果至关重要。本文对五孔探针在气速测量相关方法中的应用进行说明,尤其是对在高速测量中五孔探针的使用进行详细的研究。对五孔探针在Ma>0.3的高速气流速度测量中的应用进行了研究,探讨了五孔探针在高速气流中的标定和测量方法,设计加工了锥形五孔探针,并在标准风洞0.3>Ma>1的高速流场中对其进行了标定,获得了相应的标定校核结果;通过实验分析了Ma>0.3时气流的可压缩性对气流速度测量结果的影响;针对超音速流场,从理论上分析了探针前正激波、斜激波对测量参数的影响,提出测量数据的修正方法;并在Laval喷管实验平台中使用五孔探针对气流速度进行了测量,测量结果具有较高的精度,满足工程使用要求,验证了五孔探针对气流速度测量校核和使用方法的准确性。研究结果不仅拓宽了五孔探针的应用范围,而且对相关的测量研究有重要的工程价值。 相似文献
19.
Yong-jian Zhi Bin Zhang Kai Li Xiao-yan Huang You-tong Fang Wen-ping Cao 《浙江大学学报(A卷英文版)》2011,12(12):950-956
A switched-mode unit used in electric locomotive generates a strong high frequency conducted electromagnetic interference
(EMI), which radiates electromagnetic energy through railway lines. Evaluation of magnetic field using analytical technique
based on contour integral is presented, in order to assess the electromagnetic environment around a high-speed railway. Actual
railway multiconductor finitely long overhead lines are represented by an infinitely long single line above two-layered earth,
whose characteristic is different from homogeneous earth. Owing to the constraint of the GB/T 24338-2009 and the high frequency
investigated (a few MHz), only the magnetic fields are examined. The magnetic fields consist of four components: the direct
wave, the ideal reflected wave or image wave, the trapped surface wave, and the lateral wave. The calculation results proved
that due to the presence of the trapped surface wave, the magnetic field of the observer point on the interface is strongly
influenced, when the line is on or closed to the interface. 相似文献
20.
This paper discusses the unsteady aerodynamic behavior of long-span vaulted roofs. First, a forced vibration test in a turbulent boundary layer is conducted in a wind tunnel. The models are force vibrated in the first anti-symmetric mode to investigate the effects of wind speed, rise/span ratio, and the amplitude and frequency of forced vibration on the distributions of wind pressures and unsteady aerodynamic forces. Then, a large eddy simulation (LES) is carried out to clarify the physical mechanism of wind-roof interaction as well as to investigate the influences of a roof’s vibration on the flow field around the roof. From the results of the wind tunnel experiment and the LES, we discuss the characteristics of unsteady aerodynamic forces on a long-span vaulted roof over a wide range of the reduced frequency of vibration. The effect of unsteady aerodynamic forces on the dynamic response of the roof is also discussed. A comparison between the wind tunnel experiment and the LES indicates that the LES can be used effectively to evaluate the unsteady aerodynamic behavior. 相似文献