scholarly journals A STUDY ON THE AERODYNAMIC EFFECTS WHEN A HIGH-SPEED TRAIN PASSING THROUGH AN UNDERGROUND STATION USING COMPUTATIONAL FLUID DYNAMICS

2016 ◽  
Vol 21 (4) ◽  
pp. 61-70
Author(s):  
K.M. Lim ◽  
Y.M. Kim ◽  
M.S. Bang ◽  
H.B. Kwon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
High Speed Train ◽  
Underground Station

On computational fluid dynamics modelling of crosswind effects for high-speed rolling stock

2003 ◽  
Vol 217 (3) ◽  
pp. 203-226 ◽  
Author(s):  
B Diedrichs
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Flow Simulation ◽  
Sensitivity Study ◽  
Simulation Software ◽  
Rolling Stock ◽  
High Speed Train ◽  
Crosswind Stability ◽  
Deutsche Bahn

This work addresses crosswind stability exemplified for the German Railway Deutsche Bahn AG high-speed train ICE 2. The scope of the work is to describe the flow by means of computational fluid dynamics past the leading two cars of the train for yaw angles in the range 12.2–40.0°. Three track formations are utilized. The basic results are the set of independent aerodynamic coefficients for the lead and subsequent cars. The results are to some extent compared with experimental data for ICE 2 and also with data obtained for the Swedish high-speed train X2000. A numerical sensitivity study is undertaken to quantify differences in the above results dependent on the grid density and quality, turbulence model, numerical scheme, location of inlet and outlet boundaries, turbulence intensity and flow simulation software.

scholarly journals CFD analysis on the aerodynamics characteristics of Jakarta-Bandung high speed train

2018 ◽  
Vol 159 ◽  
pp. 02038 ◽  
Author(s):  
Tony Utomo ◽  
Berkah Fajar ◽  
Hendry Arpriyanto
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
High Speed ◽  
Computational Domain ◽  
Cfd Analysis ◽  
High Speed Train ◽  
Pressure Area ◽  
Train Speed ◽  
Simulation Results

In this study, the aerodynamics characteristics of HST type CRH380A which is planned to be operated on the new railway of Jakarta-Bandung are analysed using Computational Fluid Dynamics. The speed of the train in this simulation was varied from 100 km/h to a maximum designed speed of 350 km/h with the increment of 30 km/h. The train was modelled in 3D computational domain with more than 1.7 million cells. The turbulence model employed in this study was standard k-ω. The simulation results show that the drag coefficient (CD) is slightly decrease by the increase of speed. At the speed of 100 km/h the CD is 0.216 and decrease to 0.188 at the speed of 350 km/h. The high pressure area is located at the nose of the train. The pressure acting on this location is increase with the increase of the train speed.

Effect of the inter-car gap length on the aerodynamic characteristics of a high-speed train

2018 ◽  
Vol 233 (4) ◽  
pp. 448-465 ◽  
Author(s):  
Tian Li ◽  
Ming Li ◽  
Zheng Wang ◽  
Jiye Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Drag Force ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Wind Tunnel Experiments ◽  
The Impact

In wind tunnel experiments, the inter-car gaps are designed in such a way as to separate the force measurements for each car and prevent the interference between cars during tests. Moreover, the inter-car gap has a significant effect on the aerodynamic drag of a train. In order to guide the design of the inter-car gaps between cars in wind tunnel experiments, the impact of the inter-car gap length on the aerodynamic characteristics of a 1/8th scale high-speed train is investigated using computational fluid dynamics. The shear stress transport k-ω model is used to simulate the flow around a high-speed train. The aerodynamic characteristics of the train with 10 different inter-car gap lengths are numerically simulated and compared. The 10 different inter-car gap lengths are 5, 8, 10, 15, 20, 30, 40, 50, 60, and 80 mm. Results indicate that the aerodynamic drag coefficients obtained using computational fluid dynamics fit the experimental data well. Rapid pressure variations appear in the upper and lower parts of the inter-car gaps. With the increase of the inter-car gap length, the drag force coefficient of the head car gradually increases. The total drag force coefficients of the trains with the inter-car gap length less than 10 mm are practically equal to those of the trains without inter-car gaps. Therefore, it can be concluded from the present study that 10 mm is recommended as the inter-car gap length for the 1/8th scale high-speed train models in wind tunnel experiments.

scholarly journals A comparative study of methods to simulate aerodynamic flow beneath a high-speed train

2017 ◽  
Vol 232 (5) ◽  
pp. 1464-1482 ◽  
Author(s):  
David Soper ◽  
Dominic Flynn ◽  
Chris Baker ◽  
Adam Jackson ◽  
Hassan Hemida
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Simulations ◽  
High Speed ◽  
Experimental Studies ◽  
Model Tests ◽  
Full Scale ◽  
High Speed Train ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

The introduction of dedicated high-speed railway lines around the world has led to issues associated with running trains at very high speeds. Aerodynamic effects proportionally increase with train speed squared; consequently, at higher speeds aerodynamic effects will be significantly greater than those of trains travelling at lower speeds. On ballasted track beds, the phenomenon in which ballast particles become airborne during the passage of a high-speed train has led to the need for understanding the processes involved in train and track interaction (both aerodynamical and geotechnical). The difficulty in making full-scale aerodynamic measurements beneath a high-speed train has created the requirement to be able to accurately simulate these complex aerodynamic flows at the model scale. In this study, the results of moving-model tests and numerical simulations were analysed to determine the performance of each method for simulating the aerodynamic flow underneath a high-speed train. Validation was provided for both cases by juxtaposing the results against those from full-scale measurements. The moving-model tests and numerical simulations were performed at the 1/25th scale. Horizontal velocities from the moving-model tests and computational fluid dynamics simulations were mostly comparable except those obtained close to the ballast. In this region, multi-hole aerodynamic probes were unable to accurately measure velocities. The numerical simulations were able to resolve the flow to much smaller turbulent scales than could be measured in the experiments and showed an overshoot in peak velocity magnitudes. Pressure and velocity magnitudes were found to be greater in the numerical simulations than in the experimental tests. This is thought to be due to the influence of ballast stones in the experimental studies allowing the flow to diffuse through them, whereas in the computational fluid dynamics simulations, the flow stagnated on a smooth non-porous surface. Additional validation of standard deviations and turbulence intensities found good agreement between the experimental data but an overshoot in the numerical simulations. Both moving model and computational fluid dynamics techniques were shown to be able to replicate the flow development beneath a high-speed train. These techniques could therefore be used as a method to model underbody flow with a view to train homologation.

scholarly journals Aerodynamic analysis of uphill drafting in cycling

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
T. van Druenen ◽  
B. Blocken
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Scientific Literature ◽  
Sensitivity Analyses ◽  
Air Resistance ◽  
Wind Tunnel Measurements ◽  
Aerodynamic Effect ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

AbstractSome teams aiming for victory in a mountain stage in cycling take control in the uphill sections of the stage. While drafting, the team imposes a high speed at the front of the peloton defending their team leader from opponent’s attacks. Drafting is a well-known strategy on flat or descending sections and has been studied before in this context. However, there are no systematic and extensive studies in the scientific literature on the aerodynamic effect of uphill drafting. Some studies even suggested that for gradients above 7.2% the speeds drop to 17 km/h and the air resistance can be neglected. In this paper, uphill drafting is analyzed and quantified by means of drag reductions and power reductions obtained by computational fluid dynamics simulations validated with wind tunnel measurements. It is shown that even for gradients above 7.2%, drafting can yield substantial benefits. Drafting allows cyclists to save over 7% of power on a slope of 7.5% at a speed of 6 m/s. At a speed of 8 m/s, this reduction can exceed 16%. Sensitivity analyses indicate that significant power savings can be achieved, also with varying bicycle, cyclist, road and environmental characteristics.

Slam load estimation for high-speed catamarans in irregular head seas by full-scale computational fluid dynamics

2021 ◽  
Vol 234 ◽  
pp. 109160
Author(s):  
Islam Almallah ◽  
Jason Ali-Lavroff ◽  
Damien S. Holloway ◽  
Michael R. Davis
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Full Scale ◽  
Load Estimation

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.

Transient Computational Fluid Dynamics/Discrete Element Method Simulation of Gas–Solid Flow in a Spouted Bed and Its Validation by High-Speed Imaging Experiment

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Ling Zhou ◽  
Lingjie Zhang ◽  
Weidong Shi ◽  
Ramesh Agarwal ◽  
Wei Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Discrete Element Method ◽  
Fluidized Bed ◽  
High Speed ◽  
Discrete Element ◽  
Bubble Shape ◽  
High Speed Imaging ◽  
Bed Height ◽  
Simulation Results

A coupled computational fluid dynamics (CFD)/discrete element method (DEM) is used to simulate the gas–solid two-phase flow in a laboratory-scale spouted fluidized bed. Transient experimental results in the spouted fluidized bed are obtained in a special test rig using the high-speed imaging technique. The computational domain of the quasi-three-dimensional (3D) spouted fluidized bed is simulated using the commercial CFD flow solver ANSYS-fluent. Hydrodynamic flow field is computed by solving the incompressible continuity and Navier–Stokes equations, while the motion of the solid particles is modeled by the Newtonian equations of motion. Thus, an Eulerian–Lagrangian approach is used to couple the hydrodynamics with the particle dynamics. The bed height, bubble shape, and static pressure are compared between the simulation and the experiment. At the initial stage of fluidization, the simulation results are in a very good agreement with the experimental results; the bed height and the bubble shape are almost identical. However, the bubble diameter and the height of the bed are slightly smaller than in the experimental measurements near the stage of bubble breakup. The simulation results with their experimental validation demonstrate that the CFD/DEM coupled method can be successfully used to simulate the transient gas–solid flow behavior in a fluidized bed which is not possible to simulate accurately using the granular approach of purely Euler simulation. This work should help in gaining deeper insight into the spouted fluidized bed behavior to determine best practices for further modeling and design of the industrial scale fluidized beds.

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