Ballasted track aerodynamic optimization by wind tunnel test and CFD simulation

2020 ◽  
pp. 095440972096088
Author(s):  
Guoqing Jing ◽  
Dong Ding ◽  
Le Fang
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Cfd Simulation ◽  
Wind Tunnel Test ◽  
Wind Pressure ◽  
Aerodynamic Optimization ◽  
Great Probability ◽  
Sliding Mesh ◽  
Ballasted Track ◽  
Set Up

Ballast flight problem sets back high-speed railway development, which causing damages to train and rail. The present paper puts forward wind tunnel tests and CFD simulation to study ballast flight mechanisms and ballasted track aerodynamics. A 1:1 scale ballasted track model was set up to analyze ballast flight phenomena, where aerodynamics influencing factors and impacts on ballast bed were investigated. A numerical model of CRH3 train-ballast bed was built by combining the Realizable k- ϵ viscous model and sliding mesh technique. CFD model with the above method was used to investigate aerodynamic effects as well as the mechanism of ballast flight, thus providing the theoretical basis for optimizing ballast bed profile and preventing ballast flight. Results show that pressure distribution exhibits large value at the center of the ballasted track and decreases at track edge. The head, tail and bogie area of the train result in large fluctuation of wind pressure, which has a great probability of ballast flight. Appropriate countermeasures should be taken, such as reduce shoulder ballast height and crib ballast could be effective methods to decrease the probability of ballast flight.

scholarly journals Galloping Stability and Wind Tunnel Test of Iced Quad Bundled Conductors considering Wake Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xiaohui Liu ◽  
Ming Zou ◽  
Chuan Wu ◽  
Mengqi Cai ◽  
Guangyun Min ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Transmission Lines ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Aerodynamic Coefficients ◽  
Wake Effect ◽  
Aerodynamic Coefficient ◽  
Set Up ◽  
The Stability ◽  
Three Degrees Of Freedom

A new quad bundle conductor galloping model considering wake effect is proposed to solve the problem of different aerodynamic coefficients of each subconductor of iced quad bundle conductor. Based on the quasistatic theory, a new 3-DOF (three degrees of freedom) galloping model of iced quad bundle conductors is established, which can accurately reflect the energy transfer and galloping of quad bundle conductor in three directions. After a series of formula derivations, the conductor stability judgment formula is obtained. In the wind tunnel test, according to the actual engineering situation, different variables are set up to accurately simulate the galloping of iced quad bundle conductor under the wind, and the aerodynamic coefficient is obtained. Finally, according to the stability judgment formula of this paper, calculate the critical wind speed of conductor galloping through programming. The dates of wind tunnel test and calculation in this paper can be used in the antigalloping design of transmission lines.

Sailing Yacht Rig Improvements Through Viscous Computational Fluid Dynamics

2005 ◽  
Author(s):  
Vincent G. Chapin ◽  
Romaric Neyhousser ◽  
Stephane Jamme ◽  
Guillaume Dulliand ◽  
Patrick Chassaing
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
High Speed ◽  
Stokes Equations ◽  
Wind Tunnel Test ◽  
Physical Modelling ◽  
Optimized Design ◽  
Linear Interaction ◽  
Sailing Yacht

In this paper we propose a rational viscous Computational Fluid Dynamics (CFD) methodology applied to sailing yacht rig aerodynamic design and analysis. After an outlook of present challenges in high speed sailing, we emphasized the necessity of innovation and CFD to conceive, validate and optimize new aero-hydrodynamic concepts. Then, we present our CFD methodology through CAD, mesh generation, numerical and physical modelling choices, and their validation on typical rig configurations through wind-tunnel test comparisons. The methodology defined, we illustrate the relevance and wide potential of advanced numerical tools to investigate sailing yacht rig design questions like the relation between sail camber, propulsive force and aerodynamic finesse, and like the mast-mainsail non linear interaction. Through these examples, it is shown how sailing yacht rig improvements may be drawn by using viscous CFD based on Reynolds Averaged Navier-Stokes equations (RANS). Then the extensive use of viscous CFD, rather than wind-tunnel tests on scale models, for the evaluation or ranking of improved designs with increased time savings. Viscous CFD methodology is used on a preliminary study of the complex and largely unknown Yves Parlier Hydraplaneur double rig. We show how it is possible to increase our understanding of his flow physics with strong sail interactions, and we hope this methodology will open new roads toward optimized design. Throughout the paper, the necessary comparison between CFD and wind-tunnel test will be presented to focus on limitations and drawbacks of viscous CFD tools, and to address future improvements.

Videogrammetric Techniques for Wind Tunnel Testing and Applications

2014 ◽  
Vol 986-987 ◽  
pp. 1629-1633
Author(s):  
Zheng Yu Zhang ◽  
Xu Hui Huang ◽  
Jiang Yin ◽  
Han Xuan Lai
Keyword(s):  
Wind Tunnel ◽  
Wave Front ◽  
High Speed ◽  
Marked Point ◽  
Wind Tunnel Test ◽  
Wind Tunnels ◽  
Test Model ◽  
Wind Tunnel Testing ◽  
Section Size ◽  
Key Techniques

Videogrammetric measurement is a research focus for the organizations of wind tunnel test because of its no special requirements on the test model, its key techniques for the vibration environment of the high speed wind tunnel are introduced by this paper, such as the solution of exterior parameters with big-angle large overlap, the algorithm of image processing for extracting marked point, the method of camera calibration and wave-front distortion field measurement. The great requirements and application prospects of videogrammetry in wind tunnel fine testing have been demonstrated by several practice experiments, including to measure test model’s angle of attack, dynamic deformations and wave-front distortion field in high speed wind tunnels whose test section size is 2 meters.

Interaction Between Wind Loading and Japanese Slates: Effect on Vibration and Scattering

2008 ◽  
Author(s):  
Satoru Okamoto
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Natural Frequencies ◽  
Basic Mechanism ◽  
Video Camera ◽  
Flow Speed ◽  
Test Method ◽  
Wind Loading ◽  
Natural Mode ◽  
Set Up

A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.

Wind Pressure Coefficients Determination for Pre-Homogenization Storage in Cement Mill

2011 ◽  
Vol 94-96 ◽  
pp. 1026-1030
Author(s):  
Yue Ming Luo ◽  
Yue Yin ◽  
Xi Liang Liu
Keyword(s):  
Wind Tunnel ◽  
Spherical Shell ◽  
Rapid Development ◽  
Wind Tunnel Test ◽  
Wind Pressure ◽  
Wind Engineering ◽  
Pressure Coefficients ◽  
Continuous Innovation ◽  
Structural Style ◽  
Wind Pressures

Due to the increasing of wind disaster, structural wind engineering arouses more and more attention recently, with rapid development on spatial structure and continuous innovation of structural style. The main purpose of structural wind engineering is to calculate the wind pressure coefficients of structure. In this paper, the numerical wind tunnel method (NWTM), based on the Computational Fluid Dynamics (CFD), is applied to study wind load. The wind pressure coefficients of reticulated spherical shell with the 4.6m high wall were first determined, using the NWTM. The results are then compared with the wind tunnel test (WTT) and good agreement is found. The feasibility and reliability of NWTM were then verified. As the second example, NWTM is carried out to predict wind-induced pressure on reticulated spherical shell without wall. Further the distribution behavior of wind pressures on this kind of structures is discussed which could provide professionals the reference for the design of structure.

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.

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