Abstract
Mixed passenger and freight railway is a common form in rail transportation, while the intersection of a streamlined
electric-multiple-unit (EMU) train and a blunt freight train in a same tunnel may lead to unforeseen adverse effects due to
differences in shape configurations. This paper examines the aerodynamic interactions that occur when these two types of trains
pass each other in a tunnel. A three-dimensional, compressible, and unsteady Reynolds-Averaged Navier-Stokes (URANS)
equations along with the RNG k-ε turbulence model is employed for numerical solution, which was validated by experiments.
The results indicate that the freight train experienced 45% higher initial compressive pressure rise and a 75% greater initial
pressure gradient compared to the EMU upon tunnel entry. However, the peak-to-peak pressure for leading car of the EMU is
39% greater than that of the freight train, with an average increase of 18% per vehicle. Slipstream analysis shows the EMU has
uniform rearward flow at both sides, while the freight train exhibits asymmetric slipstream directions. During the intersection of
EMU and freight trains, the average drag on the freight train's leading car is 65% higher than that on the EMU. However, the
maximum peak-to-peak lateral force occurs when the noses of the freight train and EMU meet, with the EMU exhibiting a 23%
higher risk of overturning compared to the freight train. The findings could inform the practical engineering operations related to
mixed passenger and freight railway.
Address
Wenhui Li:1)School of Rail Transportation, Soochow University, Suzhou, Jiangsu 215131, PR China
2)Intelligent Urban Rail Engineering Research Center of Jiangsu Province, Suzhou, 215131, PR China
Yifan Gu:1)School of Rail Transportation, Soochow University, Suzhou, Jiangsu 215131, PR China
2)Intelligent Urban Rail Engineering Research Center of Jiangsu Province, Suzhou, 215131, PR China
Yelin Deng:1)School of Rail Transportation, Soochow University, Suzhou, Jiangsu 215131, PR China
2)Intelligent Urban Rail Engineering Research Center of Jiangsu Province, Suzhou, 215131, PR China
Weifeng Zhao:1)School of Rail Transportation, Soochow University, Suzhou, Jiangsu 215131, PR China
2)Intelligent Urban Rail Engineering Research Center of Jiangsu Province, Suzhou, 215131, PR China
Xueliang Fan:1)School of Rail Transportation, Soochow University, Suzhou, Jiangsu 215131, PR China
2)Intelligent Urban Rail Engineering Research Center of Jiangsu Province, Suzhou, 215131, PR China
Abstract
Flexible suspended pedestrian bridge (FSPB) is a distinctive structure with a taut catenary shape in which separated
deck modules are supported by suspension cables. FSPBs are characterized by high flexibility and large deformation arcs due to
their low structural stiffness and damping, exhibiting significant aeroelastic interactions between modes. This study focused on
flutter, an aeroelastic instability issue, in FSPBs. Wind tunnel tests and numerical analyses were conducted on two deck designs:
open grating (OG), which minimizes air resistance, and solid deck (SD), which fully blocks the deck grating. Results showed
that SD exhibited relatively vulnerable aeroelastic behavior, while the OG demonstrated greater stability against flutter.
Numerical analysis explored the mode coupling of the entire bridge, examining the influence of lateral modes and degrees of
freedom (DOF) on the onset of coupled flutter in the SD. The applicability of a two-dimensional (2-D) wind tunnel test setup
was also examined. Additionally, the study identified the developing mechanism of torsional-vertical coupled flutter and key
parameters influencing critical modes using 2-D wind tunnel tests and time-domain flutter analysis.
Key Words
aeroelastic flutter analysis; coupled flutter; flexible suspended pedestrian bridge (FSPB); wind tunnel test
Address
Sanghyeon Lee:Department of Civil and Environmental Engineering, Seoul National University, Seoul, 08826, Republic of Korea
Youchan Hwang:Floating Infrastructure Research Center, Seoul National University, Seoul, 08826, Republic of Korea
Ho-Kyung Kim:1)Department of Civil and Environmental Engineering, Seoul National University, Seoul, 08826, Republic of Korea
2)Floating Infrastructure Research Center, Seoul National University, Seoul, 08826, Republic of Korea
3)Institute of Construction and Environmental Engineering, Seoul National University, Seoul, 08826, Republic of Korea
Abstract
This study generated three types of turbulence fields in a wind tunnel by changing the size of grid holes and grid
plates. The buffeting force characteristics of the main beam under different turbulent flow fields are discussed. In addition, the
narrowband synthetic random flow generation (NSRFG) turbulent inlet method was used to conduct large eddy simulation
(LES) of -shaped beam under
different turbulent inflow flows-shaped beams. This study presents a grid generation strategy for LES based on the NSRFG, discusses the horizontal
decay law of turbulent wind parameters, and provides a method for setting inlet turbulent wind parameters. Finally, proper
orthogonal decomposition (POD) was carried out by extracting the numerical simulation data of key parts around the main
beam, and the influence mechanism of the turbulent wind parameters on the buffeting force was discussed. The results indicate
that the mean wind speed and turbulence intensity have relatively small effects on the horizontal decay function of the
turbulence parameters. By contrast, the turbulent integral scale has a significant impact on the horizontal decay function of the
turbulent wind parameters. Turbulence parameters can change the intensity, position, and shape of the vortices around the model,
thereby altering its surface pressure.
Key Words
decay law; LES; POD; turbulent wind parameters;
Address
Zhengfeng Shen:1)School of Architecture and Civil Engineering, West Anhui University, Lu'an, 237012, Anhui, China
2)Department of Structure Engineering, Tongji University, Shanghai, 200092, China
3)Changjiang Jinggong Steel Structure (Group) Co., Ltd, Lu'an, 237161, Anhui, China
Feng Wang:School of Highway, Chang'an University, Xi'an, 710064, Shaanxi, China
Chengdong Feng:Tianjin Key Laboratory of Prefabricated Buildings and Intelligent Construction, School of Civil and Transportation Engineering,
Hebei University of Technology, Tianjin 300401, China
Abstract
As train speed becomes faster, the aerodynamic load they face also increases, which can create safety risks for
maglev trains when two trains meet. To address this, the computational fluid dynamic (CFD) approach was used to assess the
aerodynamic coefficients of the guideway and the vehicles. The aerodynamic pressure of the vehicle surface, which is obtained
by CFD, is verified by field measurement results. Then, a dynamic analysis model of maglev train-guideway systems under the
train-induced wind effect was presented. Finally, the dynamic responses of the maglev trains and the guideways during the
meeting of the two trains were analyzed. The effects of train speed and line spacing were explored in detail. The results show
that the change of the aerodynamic coefficients of the head car of the 3-car train is the most drastic during the meeting of the two
trains. Coupling vibration analyses demonstrate that there are strong effects on the lateral vibration of the car body and less
impact on the guidance gap. When the train speed is 430 km/h, the peak values of acceleration for two trains passing each other
are approximately five times as large as that of a single train passing. On this basis, an optimization measure is proposed, and the
line spacing of the maglev line is increased from 5.1 m to 5.6 m, which will greatly reduce the aerodynamic coefficient and
lateral acceleration of the train by about 20%.
Key Words
aerodynamic coefficient; dynamic response; maglev train-guideway system; meeting of two trains; train-induced
wind effect
Address
Xiangfu Tian:1)State Key Laboratory of Rail Transit Vehicle System, Southwest Jiaotong University, Chengdu 610031, China
2)State Key Laboratory of Bridge Intelligent and Green Construction, Southwest Jiaotong University, 611756 Chengdu, China
Huoyue Xiang:State Key Laboratory of Bridge Intelligent and Green Construction, Southwest Jiaotong University, 611756 Chengdu, China
Hao Hu:State Key Laboratory of Bridge Intelligent and Green Construction, Southwest Jiaotong University, 611756 Chengdu, China
Yongle Li:1)State Key Laboratory of Rail Transit Vehicle System, Southwest Jiaotong University, Chengdu 610031, China
2)State Key Laboratory of Bridge Intelligent and Green Construction, Southwest Jiaotong University, 611756 Chengdu, China
Abstract
Significant vertical displacement caused by ice shedding from conductors may increase the risk of electrical
accidents such as flashover. Ice shedding often occurs with joint actions of wind, which affects the jump height of transmission
lines. The shielding effect of bundled conductors leads to uneven ice accretion among sub-conductors, resulting in variations in
the wind attack angle along the transmission line, which significantly influences on the wind load on the conductor. This paper
firstly established a finite element model of a practical iced transmission line for dynamic response analysis of ice shedding. To
accurately determine the wind load on bundled conductors, the aerodynamic force coefficients of the conductors were updated in
real-time by extracting the torsion angle response. Parametric analysis was also conducted in detail to investigate the impact of
uneven ice accretion among sub-conductors, ice thickness, and wind velocity on the iced-shedding jump height of the
transmission line.
Address
Mingfeng Huang:1)College of Civil Engineering and Architecture, Zhejiang University, 886 Yuhangtang Road, Xihu District, Hangzhou, China
2)College of Civil Engineering and Architecture, Guangxi University, 100 East Daxue Road, Xixiangtang District, Nanning, China
Changzheng Chi:College of Civil Engineering and Architecture, Zhejiang University, 886 Yuhangtang Road, Xihu District, Hangzhou, China
Yi Gu:China Energy Engineering Group Zhejiang Electric Power Design Institute Co., Ltd., 68 Gucui Road, Xihu District, Hangzhou, China
Yuelong Zhang:China Energy Engineering Group Zhejiang Electric Power Design Institute Co., Ltd., 68 Gucui Road, Xihu District, Hangzhou, China
Zidi Zhu:College of Civil Engineering and Architecture, Zhejiang University, 886 Yuhangtang Road, Xihu District, Hangzhou, China
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