scholarly journals Study on aerodynamic characteristics and running safety of two high-speed trains passing each other under crosswinds based on computer simulation technologies

2017 ◽  
Vol 19 (8) ◽  
pp. 6328-6345
Author(s):  
Hong Wu ◽  
Zhi-jian Zhou
Keyword(s):  
Computer Simulation ◽  
High Speed ◽  
Aerodynamic Characteristics ◽  
Running Safety ◽  
High Speed Trains

The Aerodynamic Characteristics of the Pantograph When the Train Passes Through the Tunnel

2017 ◽  
Author(s):  
Dilong Guo ◽  
Wen Liu ◽  
Junhao Song ◽  
Ye Zhang ◽  
Guowei Yang
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Maximum Amplitude ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Expansion Waves ◽  
Compression And Expansion ◽  
High Speed Trains ◽  
Current Characteristics ◽  
Pass Through

The aerodynamic force acting on the pantograph by the airflow is obviously unsteady and has a certain vibration frequency and amplitude, while the high-speed train passes through the tunnel. In addition to the unsteady behavior in the open-air operation, the compressive and expansion waves in the tunnel will be generated due to the influence of the blocking ratio. The propagation of the compression and expansion waves in the tunnel will affect the pantograph pressure distribution and cause the pantograph stress state to change significantly, which affects the current characteristics of the pantograph. In this paper, the aerodynamic force of the pantograph is studied with the method of the IDDES combined with overset grid technique when high speed train passes through the tunnel. The results show that the aerodynamic force of the pantograph is subjected to violent oscillations when the pantograph passes through the tunnel, especially at the entrance of the tunnel, the exit of the tunnel and the expansion wave passing through the pantograph. The changes of the pantograph aerodynamic force can reach a maximum amplitude of 106%. When high-speed trains pass through tunnels at different speeds, the aerodynamic coefficients of the pantographs are roughly the same.

Study on Derailment Mechanism and Safety Operation Area of High-Speed Trains Under Earthquake

2012 ◽  
Vol 7 (4) ◽  
Author(s):  
Liang Ling ◽  
Xinbiao Xiao ◽  
Xuesong Jin
Keyword(s):  
High Speed ◽  
Dynamical Behavior ◽  
Vehicle Speed ◽  
Vertical Force ◽  
Explicit Integration ◽  
Running Safety ◽  
Earthquake Motion ◽  
High Speed Trains ◽  
Wheel Loading ◽  
Safety Operation

In order to investigate the derailment mechanism and safety operation area of high-speed trains under earthquake, a coupled vehicle-track dynamic model considering earthquake effect is developed, in which the vehicle is modeled as a 35 degrees of freedom (DOF) multibody system with nonlinear suspension characteristic and the slab track is modeled as a discrete elastic support model. The rails of the track are assumed to be Timoshenko beams supported by discrete rail fasteners, and the slabs are modeled with solid finite elements. The system motion equations are solved by means of an explicit integration method in time domain. The present work analyzes in detail the effect of earthquake characteristics on the dynamical behaviors of a vehicle-track coupling system and the transient derailment criteria. The considered derailment criteria include the ratio of the wheel/rail lateral force to the vertical force, the wheel loading reduction, the wheel/rail contact point traces on the wheel tread, and the wheel rise with respect to the rail top, respectively. The present work also finds the safety operation area, the derailment area, and the warning area of high-speed trains under earthquake, and their boundaries. These areas consist of three key parameters influencing the dynamical behavior of high-speed train and track under earthquake. The three key influencing parameters are, respectively, the vehicle speed and the lateral and vertical peak ground acceleration (PGA) of an earthquake. The results obtained indicate that the lateral earthquake motion has a greater influence on the vehicle dynamic behavior and its running safety compared to the vertical earthquake motion. The risk of derailment increases quickly with the increasing of lateral earthquake motion amplitude. The lateral earthquake motion is dominant in the vehicle running safety influenced by an earthquake. While the vertical earthquake motion promotes jumping of the wheels easily, not easy is flange climb derailment. And the effect of the vehicle speed is not significant under earthquake.

Efficient evaluation of bridge deformation for running safety of railway vehicles using simplified models

2019 ◽  
Vol 23 (3) ◽  
pp. 454-467
Author(s):  
Zhibin Jin ◽  
Ligang Yuan ◽  
Shiling Pei
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Hertz Contact ◽  
Angular Rotation ◽  
Running Safety ◽  
High Speed Trains ◽  
Constraint Model ◽  
Response Errors ◽  
Large Wheel ◽  
Wheel Track

The running safety of high-speed trains over bridges is a great concern in bridge design. Typically, the running safety of vehicles is evaluated by vehicle–track simulations that are computationally expensive and unfamiliar to bridge designers. This study investigates simplified vehicle–track models for assessing the running safety of vehicles on deformed bridges. Four types of simplified vehicle models along with four types of simplified wheel–track models are investigated. The predicted wheel–rail forces are compared with those simulated by the detailed vehicle–track program. In these simulations, typical bridge deformations are taken as excitations to the dynamic system. It is found that omitting the rail vibration leads to large wheel–rail response errors. The wheel–rail constraint model gives similar wheel–rail responses to those obtained by the Hertz contact model. A vehicle–track model with five degrees-of-freedom is adequate for assessing wheel–rail forces. Furthermore, an analytical solution to the wheel–rail forces running over an angular rotation was obtained. These simplified vehicle–track models provide an efficient way to assess the running safety of vehicles on deformed bridges when using probabilistic or optimal analyses that require a large number of simulations.

Mapping relationship between dynamic responses of high-speed trains and additional bridge deformations

2020 ◽  
pp. 107754632093689
Author(s):  
Hongye Gou ◽  
Chang Liu ◽  
Hui Hua ◽  
Yi Bao ◽  
Qianhui Pu
Keyword(s):  
High Speed ◽  
Coupled Model ◽  
Dynamic Responses ◽  
High Speed Railway ◽  
Railway Bridges ◽  
Running Safety ◽  
High Speed Trains ◽  
Track Bridge ◽  
The Relationship ◽  
Track Deformation

Deformations of high-speed railways accumulate over time and affect the geometry of the track, thus affecting the running safety of trains. This article proposes a new method to map the relationship between dynamic responses of high-speed trains and additional bridge deformations. A train–track–bridge coupled model is established to determine relationship between the dynamic responses (e.g. accelerations and wheel–rail forces) of the high-speed trains and the track deformations caused by bridge pier settlement, girder end rotation, and girder camber. The dynamic responses are correlated with the track deformation. The mapping relationship between bridge deformations and running safety of trains is determined. To satisfy the requirements of safety and riding comfort, the suggested upper thresholds of pier settlement, girder end rotation, and girder camber are 22.6 mm, 0.92‰ rad, and 17.2 mm, respectively. This study provides a method that is convenient for engineers in evaluation and maintenance of high-speed railway bridges.

Influence of Typical Subgrade Structures on Aerodynamic Characteristics of High Speed Trains in Cross Wind Conditions

2018 ◽  
Author(s):  
Zhenxu Sun ◽  
Guowei Yang
Keyword(s):  
High Speed ◽  
Aerodynamic Characteristics ◽  
Wind Condition ◽  
Safety Control ◽  
High Speed Trains ◽  
Flow Field Characteristics ◽  
Wind Velocities ◽  
The Cross ◽  
Train Safety

Due to geographical and environmental constraints, highspeed railways use a variety of subgrade structures such as ground, embankments with different height, viaducts, etc. When trains run on embankments and viaducts, the flow around the car body is more complex than the ground. Under the action of crosswind, there are obvious differences in the cross-wind aerodynamic characteristics of high-speed trains on different subgrade structures. The unreasonable subgrade structure will affect the cross-wind safety of the train. At the same time, the structure of the train is complex, the bogie and pantograph have an important role on the flow field characteristics of the train, and the over simplified profile of the short train cannot accurately reflect the true aerodynamic characteristics of the train. In the present paper, in order to study the influence of typical subgrade structure on the aerodynamic characteristics of high speed trains, a real high-speed train with 9 carriages at the speed of 200 km/h was taken for case study, and the details of windshields, bogies and pantographs were taken into consideration. The cross wind velocities were chosen as 20, 30, 35 and 40 m/s. The aerodynamics performance of the highspeed train under the four conditions of plane ground, 3m-embankment, 6m-embankment and viaduct were simulated and compared, and the differences and regularities in the aerodynamic characteristics under cross wind conditions on different subgrade were analyzed. The results provide a reference for train safety control on complex subgrade structures under cross wind condition.

scholarly journals Influence of pantograph fixing position on aerodynamic characteristics of high-speed trains

2017 ◽  
Vol 25 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Liang Zhang ◽  
Jiye Zhang ◽  
Tian Li ◽  
Weihua Zhang
Keyword(s):  
High Speed ◽  
Aerodynamic Characteristics ◽  
High Speed Trains
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