scholarly journals Effect of Braking Plates on the Aerodynamic Behaviors of a High-Speed Train Subjected to Crosswinds

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 401
Author(s):  
Le Zhang ◽  
Tian Li ◽  
Jiye Zhang
Keyword(s):  
Drag Force ◽  
High Speed ◽  
Lift Force ◽  
Aerodynamic Force ◽  
Aerodynamic Resistance ◽  
Lateral Force ◽  
High Speed Train ◽  
Side Force ◽  
Car Body ◽  
Braking Force

Using aerodynamic resistance to provide braking force for trains is an economical braking method. It has few components to wear out and requires no energy. But the aerodynamic braking plate will significantly affect train’s aerodynamics behaviors. This paper studies the effect of the braking plates’ layout on the aerodynamic force of head car when a train is running under a crosswind. The results show that the braking plate will not only increase the drag force, but also significantly affect the lift and lateral force of the train’s head car. The installation position of the braking plates will also have a great effect on the aerodynamic force. In order to increase the drag force and weaken other aerodynamic force changes of the head car, we suggest that the first braking plate be arranged at the end of a streamlined shape, and the second braking plate be arranged at the middle of the car body. Compared with trains without braking plates, the head car’s drag force increases by 85.7%, lift force only increases by 7.6%, and side force decreases by 5.9%, when the braking plates are in operation.

Effect of the Vehicle Aerodynamics Performance under Cross Wind Condition Caused by Stiffeners

2011 ◽  
Vol 422 ◽  
pp. 747-751
Author(s):  
Xiao Hui Xiong ◽  
Xi Feng Liang
Keyword(s):  
Flow Field ◽  
Flow Separation ◽  
High Speed ◽  
Lift Force ◽  
Wind Condition ◽  
High Speed Train ◽  
Side Force ◽  
Vehicle Aerodynamics ◽  
Overturning Moment ◽  
High Speed Vehicle

New lightweight material has been applied in the vehicle manufacture of the raised speed and high speed train. In order to strength the intensity of the vehicle, some stiffeners were designed on the vehicle top. In strong cross wind, stiffeners would change the flow field distribution of the vehicle top. Phenomenon of the flow separation would occur on the part of area. In order to study the aerodynamics effected by stiffeners in cross wind, the aerodynamics performance of the 300km/h high-speed vehicle have been calculated by FLUENT when there were stiffeners on the vehicle top or not. Result obtained shows that in cross wind, the side force and the overturning moment of the vehicle with stiffeners will increase; it is greater than those of the vehicle without stiffeners. The increase values are 52.94% and 39.49%. And the lift force of the vehicle with stiffeners has some drops.

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.

scholarly journals The coupled effects of bending and torsional flexural modes of a high-speed train car body on its vertical ride quality

2019 ◽  
Vol 233 (4) ◽  
pp. 979-993 ◽  
Author(s):  
Vahid Bokaeian ◽  
Mohammad A Rezvani ◽  
Robert Arcos
Keyword(s):  
Analytical Model ◽  
Quality Index ◽  
High Speed ◽  
Ride Quality ◽  
Vertical Acceleration ◽  
Beam Model ◽  
High Speed Train ◽  
Flexural Mode ◽  
Car Body ◽  
Rail Irregularities

This study is focused on the effects of bending and torsional flexural modes of the car body on the ride quality index of a high-speed train vehicle. The Euler–Bernoulli beam model is used to extract an analytical model for a high-speed train vehicle car body in order to investigate its bending and torsional flexural vibrations. The rigid model includes a car body, two bogie frames, and four wheelsets such that, each mass has three degrees of freedom including vertical displacement, pitch motion, and roll motion. The results obtained with the proposed analytical model are compared with experimental measurements of the car body response of a Shinkansen high-speed train. Moreover, it is determined that the bending and torsional flexural modes have significant effects on the vertical acceleration of the car body, particularly in the 9–15 Hz frequency range. Furthermore, the ride quality index is calculated according to the EN 12299 standard and it is shown that the faster the train the more affected is the ride quality by the flexural modes. In addition, the effect of coherence between two rail irregularities (the right and the left rails) on the results of the simulation is investigated. The results conclude that if the irregularities are completely correlated the torsional flexural mode of the car body does not appear in the response. Also, the first bending flexural mode in such cases is more excited compared with the partially correlated or uncorrelated rail irregularities. Therefore, the ride quality index in completely correlated cases is higher than other cases.

Detached-Eddy Simulation of Ground Effect on the Wake of a High-Speed Train

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Chao Xia ◽  
Xizhuang Shan ◽  
Zhigang Yang
Keyword(s):  
Vortex Shedding ◽  
High Speed ◽  
Vortex Pair ◽  
Ground Effect ◽  
Longitudinal Vortex ◽  
High Speed Train ◽  
Detached Eddy Simulation ◽  
Side Force ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

The influence of ground effect on the wake of a high-speed train (HST) is investigated by an improved delayed detached-eddy simulation. Aerodynamic forces, the time-averaged and instantaneous flow structure of the wake are explored for both the stationary ground and the moving ground. It shows that the lift force of the trailing car is overestimated, and the fluctuation of the lift and side force is much greater under the stationary ground, especially for the side force. The coexistence of multiscale vortex structures can be observed in the wake along with vortex stretching and pairing. Furthermore, the out-of-phase vortex shedding and oscillation of the longitudinal vortex pair in the wake are identified for both ground configurations. However, the dominant Strouhal number of the vortex shedding for the stationary and moving ground is 0.196 and 0.111, respectively, due to the different vorticity accumulation beneath the train. A conceptual model is proposed to interpret the mechanism of the interaction between the longitudinal vortex pair and the ground. Under the stationary ground, the vortex pair embedded in a turbulent boundary layer causes more rapid diffusion of the vorticity, leading to more intensive oscillation of the longitudinal vortex pair.

scholarly journals Complexity Analysis on the Aerodynamic Performance of the Mega High-Speed Train Caused by the Wind Barrier on the Embankment

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-17
Author(s):  
He-xuan Hu ◽  
Wan-xin Lei ◽  
Ye Zhang
Keyword(s):  
Negative Pressure ◽  
High Speed ◽  
Complexity Analysis ◽  
Aerodynamic Force ◽  
Pressure Change ◽  
Aerodynamic Performance ◽  
Head Wave ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Negative Wave

With the world development of high-speed railways and increasing speeds, aerodynamic forces and moments acting on trains have been increased further, making trains stay at a “floated” state. Under a strong crosswind, the aerodynamic performance of a train on the embankment is greatly deteriorated; lift force and horizontal force borne by trains will be increased quickly; trains may suffer derailing or overturning more easily compared with the flat ground; train derailing will take place when the case is serious. All of these phenomena have brought risks to people’s life and properties. Hence, the paper establishes an aerodynamic model about a high-speed train passing an air barrier, computes aerodynamic forces and moments, and analyzes pulsating pressures on the train surface as well as those of unsteady flow fields around the train. Computational results indicate that when the train passed the embankment air barrier, the head wave of air pressure full wave is more than the tail wave; the absolute value of negative wave is more than that of the positive wave, which is more obvious in the head train. When the train is passing the air barrier, pressure pulsation values at head train points are more than those at other points, while pressure changes most violently at the train bottom, and pressure values close to the air barrier are more than those points far from the air barrier. Pressure values at the cross section 1 were larger than those of other points. Pressure values at measurement points of the tail train ranked the second place, with the maximum negative pressure of 1253 Pa. Pressure change amplitudes and maximum negative pressure on the train surface are increased quickly, while pressure peak values on the high-speed train surface are in direct ratio to the running speed. With the increased speed of the high-speed train, when it is running in the embankment air barrier, the aerodynamic force and moment borne by each train body are increased sharply, while the head train suffers the most obvious influences of aerodynamic effects.

Experimental Studies on Aerodynamic Characteristics of Pantograph System According to the Pantograph Cover Configurations for High Speed Train

2011 ◽  
Author(s):  
Yeongbin Lee ◽  
Minho Kwak ◽  
Kyu Hong Kim ◽  
Dong-Ho Lee
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Experimental Studies ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Experimental Models ◽  
High Speed Train ◽  
Drag And Lift

In this study, the aerodynamic characteristics of pantograph system according to the pantograph cover configurations for high speed train were investigated by wind tunnel test. Wind tunnel tests were conducted in the velocity range of 20∼70m/s with scaled experimental pantograph models. The experimental models were 1/4 scaled simplified pantograph system which consists of a double upper arm and a single lower arm with a square cylinder shaped panhead. The experimental model of the pantograph cover is also 1/4 scaled and were made as 4 different configurations. It is laid on the ground plate which modeled on the real roof shape of the Korean high speed train. Using a load cell, the aerodynamic force such as a lift and a drag which were acting on pantograph system were measured and the aerodynamic effects according to the various configurations of pantograph covers were investigated. In addition, the total pressure distributions of the wake regions behind the panhead of the pantograph system were measured to investigate the variations of flow pattern. From the experimental test results, we checked that the flow patterns and the aerodynamic characteristics around the pantograph systems are varied as the pantograph cover configurations. In addition, it is also found that pantograph cover induced to decrease the aerodynamic drag and lift forces. Finally, we proposed the aerodynamic improvement of pantograph cover and pantograph system for high speed train.

scholarly journals Influence of Rectangular Strips’ Size on Aerodynamic Performance of a High-Speed Train Subjected to Crosswind

2021 ◽  
Author(s):  
Mengying Wang ◽  
Zhenxu Sun ◽  
Shengjun Ju ◽  
Guowei Yang
Keyword(s):  
High Speed ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Orthogonal Experimental Design ◽  
High Speed Train ◽  
Force Coefficient ◽  
Roll Moment ◽  
Side Force ◽  
Moment Coefficient ◽  
Side Force Coefficient

Abstract Conventional studies usually assume that the train surface is smooth, so as to simplify the numerical calculation. In fact, the surface of the train is irregular, which will change the flow characteristics in the boundary layer and further affect the aerodynamic performance of a train. In this work, roughness is applied to the roof of a 1:25 scaled train model in the form of longitudinal strips. Firstly, the improved delayed detached eddy simulation (IDDES) method is adopted to simulate the aerodynamic performance of the train model with both smooth and rough surface, which are subjected to crosswind. Results show that the side force coefficient and the roll moment coefficient subjected to rough model decreased by 3.71% and 10.56% compared with the smooth model. Then, the width, height and length of the strips are selected as variables to design different numerical simulation schemes based on the orthogonal experimental design method. Through variance analysis, it can be found that four design parameters have no significant effect on the side force coefficient. Meanwhile, for the roll moment coefficient, the length of the strips in the straight region of the train has a significant effect and the width of the strips has a highly significant effect on it. These conclusions can provide a theoretical basis to improve the aerodynamic performance of the high-speed train subjected to crosswind.

scholarly journals Measures to reduce aerodynamic force acting on high-speed train in tunnel

2002 ◽  
Vol 2002.11 (0) ◽  
pp. 277-278 ◽  
Author(s):  
Masahiro SUZUKI ◽  
Hiroshi FUJIMOTO ◽  
Yutaka SAKUMA
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
High Speed Train
Sign in / Sign up

Export Citation Format

Share Document