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.

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.

Aerodynamic Characteristics Analysis of High-Speed Train on Cutting under Crosswinds

2013 ◽  
Vol 300-301 ◽  
pp. 62-67
Author(s):  
Kun Ye ◽  
Ren Xian Li
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Cutting Depth ◽  
Cutting Slope ◽  
Characteristics Analysis ◽  
Relationship Of ◽  
The Relationship

Cutting is an effective device to reduce crosswind loads acting on trains. The cutting depth, width and gradient of slope are important factors for design and construction of cutting. Based on numerical analysis methods of three-dimensional viscous incompressible aerodynamics equations, aerodynamic side forces and yawing moments acting on the high-speed train, with different depths and widths of cutting，are calculated and analyzed under crosswinds，meanwhile the relationship of the gradient of cutting slope and transverse aerodynamic forces acting on trains are also studied. Simulation results show that aerodynamic side forces and yawing moments acting on the train（the first, middle and rear train）decrease with the increase of cutting depth. The relationship between transverse forces (moments) coefficients acting on the three sections and the cutting depth basically is the three cubed relation. The bigger is cutting width，the worse is running stability of train. The relationship between yawing moments coefficients acting each body of the train and the cutting width approximately is the three cubed relation. The transverse Aerodynamic forces decreased gradually with the increase of the gradient of cutting slope, the relationship between yawing moments coefficients acting each body of the train and the gradient of cutting slope basically is the four cubed relation.

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

G0705 LES Analysis of Pressure Change Generated by a High-speed Train Passing Through a Tunnel

2013 ◽  
Vol 2013 (0) ◽  
pp. _G0705-01_-_G0705-02_ ◽  
Author(s):  
Sho NAKAYAMA ◽  
Makoto TSUBOKURA ◽  
Yukinobu ABE ◽  
Keiji ONISHI ◽  
Nobuyuki OSHIMA
Keyword(s):  
High Speed ◽  
Pressure Change ◽  
High Speed Train

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.

Measures to Reduce the Lateral Vibration of the Tail Car in a High Speed Train

1996 ◽  
Vol 210 (2) ◽  
pp. 87-93 ◽  
Author(s):  
H Fujimoto ◽  
M Miyamoto
Keyword(s):  
Vibration Amplitude ◽  
High Speed ◽  
Vibration Mode ◽  
Simulation Analysis ◽  
Lateral Vibration ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Vibration Data ◽  
Tunnel Section ◽  
Train Vibration

From the vibration data obtained simultaneously on several cars in the same Shinkansen train, it was observed that the vibration amplitude of the tail car is greater than those of the other cars in a train. The authors' analysis arrived at the conclusion that the vibration mode of a train has a tendency for the tail car to vibrate more than the others, when the carbody hunting characteristics of a train for the yawing mode are likely to emerge, and when aerodynamic forces work in a tunnel section. Referring to those results, by simulation analysis etc., it was found that two longitudinal dampers installed parallel between the car ends (Fig. 1) with their forces depending on the angular velocity between cars, are effective in decreasing the train vibration including the tail car's vibration. Then, the prototype of the longitudinal dampers between the cars for Shinkansen was designed by obtaining the proper damping coefficient through simulation. The effectiveness of the installed damper was verified when it was tested up to 310 km/h in the Shinkansen 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.

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