scholarly journals Aerodynamic Performance of a High-Speed Train Passing through Three Standard Tunnel Junctions under Crosswinds

2020 ◽  
Vol 10 (11) ◽  
pp. 3664 ◽  
Author(s):  
Xiujuan Miao ◽  
Kan He ◽  
Guglielmo Minelli ◽  
Jie Zhang ◽  
Guangjun Gao ◽  
...  
Keyword(s):  
High Speed ◽  
Tunnel Junctions ◽  
Pressure Coefficient ◽  
Aerodynamic Performance ◽  
High Speed Train ◽  
Flow Conditions ◽  
Tunnel Wall ◽  
Drag And Lift ◽  
Flat Ground ◽  
Good Agreement

The aerodynamic performance of a high-speed train passing through tunnel junctions under severe crosswind condition was numerically investigated using improved delayed detached-eddy simulations (IDDES). Three ground scenarios connected with entrances and exits of tunnels were considered. In particular a flat ground, an embankment, and a bridge configuration were used. The numerical method was first validated against experimental data, showing good agreement. The results show that the ground scenario has a large effect on the train’s aerodynamic performance. The bridge case resulted in generally smaller drag and lift, as well as a lower pressure coefficient on both the train body and the inner tunnel wall, as compared to the tunnel junctions with flat ground and embankment. Furthermore, the bridge configuration contributed to the smallest pressure variation in time in the tunnel. Overall, the study gives important insights on complicated tunnel junction scenarios coupled with severe flow conditions, that, to the knowledge of the authors, were not studied before. Beside this, the results can be used for further improvements in the design of tunnels where such crosswind conditions may occur.

Effects of infrastructure on the aerodynamic performance of a high-speed train

2020 ◽  
pp. 095440972095221
Author(s):  
Ming Wang ◽  
Xiao-Zhen Li ◽  
Jun Xiao ◽  
Hai-Qing Sha ◽  
Qi-Yang Zou
Keyword(s):  
High Speed ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
High Speed Train ◽  
Aerodynamic Coefficients ◽  
Pressure Distributions ◽  
Train Speed ◽  
Truss Bridge ◽  
Flat Ground

The aerodynamic characteristics of typical high-speed train can be affected by the operating infrastructure, which will affect the flow structure around train body. Five different infrastructure scenarios, including no infrastructure, flat ground, embankment, viaduct and truss bridge, are systemically studied. The purpose is to examine the uncertainties of aerodynamic coefficients caused by the infrastructure. Attention is drawn to variations of aerodynamic coefficients at certain yaw angles caused by the changes in crosswind and train speed. The middle car is chosen for quantifying the effects of five infrastructures by using wind tunnel test and numerical simulations, then followed by a detailed study on aerodynamic characteristics of three cars of train running on viaduct. Pressure distributions are also drawn for a better interpretation. Result shows that the uncertainties in aerodynamic coefficients becomes more obvious as the infrastructure gets complex and yaw angles get bigger. The aerodynamic coefficients of three cars with the viaduct scenario show the similar uncertainties, which are mostly affected by the change in crosswind rather than the train speed.

Effect of bogie fairings on the flow behaviours and aerodynamic performance of a high-speed train

2019 ◽  
Vol 58 (6) ◽  
pp. 890-910 ◽  
Author(s):  
Jiabin Wang ◽  
Guangjun Gao ◽  
Xiaobai Li ◽  
Xifeng Liang ◽  
Jie Zhang
Keyword(s):  
High Speed ◽  
Aerodynamic Performance ◽  
High Speed Train

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.

Passenger Train Slipstream Characterization Using a Rotating Rail Rig

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
N. Gil ◽  
C. J. Baker ◽  
C. Roberts ◽  
A. Quinn
Keyword(s):  
Boundary Layer ◽  
Turbulence Intensity ◽  
High Speed ◽  
Scale Model ◽  
High Speed Train ◽  
Measuring Time ◽  
Displacement Thickness ◽  
Time Histories ◽  
Attached Flow ◽  
Good Agreement

This paper presents the results of a new experimental technique to determine the structure of train slipstreams. The highly turbulent, nonstationary nature of the slipstreams make their measurement difficult and time consuming as in order to identify the trends of behavior several passings of the train have to be made. This new technique has been developed in order to minimize considerably the measuring time. It consists of a rotating rail rig to which a 1/50 scale model of a four car high speed train is attached. Flow velocities were measured using two multihole Cobra probes, positioned close to the model sides and top. Tests were carried out at different model speeds, although if the results were suitably normalized, the effect of model speed was not significant. Velocity time histories for each configuration were obtained from ensemble averages of the results of a large number of runs (of the order of 80). From these it was possible to define velocity and turbulence intensity contours along the train, as well as the displacement thickness of the boundary layer, allowing a more detailed analysis of the flow. Also, wavelet analysis was carried out on different runs to reveal details of the unsteady flow structure around the vehicle. It is concluded that, although this methodology introduces some problems, the results obtained with this technique are in good agreement with previous model and full scale measurements.

Numerical simulation of aerodynamic performance of a couple multiple units high-speed train

2017 ◽  
Vol 55 (5) ◽  
pp. 681-703 ◽  
Author(s):  
Ji-qiang Niu ◽  
Dan Zhou ◽  
Tang-hong Liu ◽  
Xi-feng Liang
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Aerodynamic Performance ◽  
High Speed Train ◽  
Multiple Units

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 Primary Study of Aerodynamic Performance Evaluation and Optimization of the High-Speed Train

2011 ◽  
Author(s):  
X. P. Wang ◽  
K. Cui ◽  
S. C. Hu ◽  
T. Y. Gao ◽  
G. W. Yang ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
High Speed ◽  
Aerodynamic Performance ◽  
Primary Study ◽  
High Speed Train
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