Numerical Investigation of Aerodynamic Drag on Vacuum Tube High Speed Train

2013 ◽  
Author(s):  
Sreeja Bibin ◽  
Sujay Kumar Mukherjea
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Aerodynamic Drag ◽  
Vacuum Pressure ◽  
Navier Stokes ◽  
Optimum Shape ◽  
Blockage Ratio ◽  
High Speed Train ◽  
Vacuum Tube ◽  
Turbulent Modeling

This work involves numerical simulations based on finite volume method to study the effects of different factors on the aerodynamic drag on a vacuum tube train running at subsonic and transonic speeds in a partially vacuum tunnel. Investigation includes the study of the effects of the shapes of head, tail, vacuum pressure and also blockage ratio of the tunnel on aerodynamic drag on a high speed train. The simulation is performed by using fluent software. Two dimensional, axisymmetric, compressible Navier-Stokes equations were solved by using k-ε turbulent modeling. Five different blockage ratios at five different speeds of the train have been considered. The simulated results show that, the blockage ratio and different working vacuum pressure significantly affects the aerodynamic drag of the train in a tunnel. Investigations with respect to different shapes of the head as well as that of the tail indicate the optimum shape for minimum drag.

Aerodynamic Simulation of the Air Flow beneath the High Speed Train

2012 ◽  
Vol 253-255 ◽  
pp. 2035-2040
Author(s):  
Ye Bo Liu ◽  
Zhi Ming Liu
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Air Flow ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Navier Stokes ◽  
High Speed Train ◽  
Navier Stokes Equations ◽  
Pressure Distributions ◽  
High Speed Trains

Numerical simulations were carried out to investigate the air flow and pressure distributions beneath high speed trains, based on the three-dimensional Reynolds-averaged Navier-Stokes equations with the SST k-ω two-equation turbulence model. The simulation scenarios were of the high speed train, the CRH2, running in the open air at four different speeds: 200km/h, 250km/h, 300km/h and 350km/h. The results show that, the highest area of pressure is located at the front underbody part of the train whist the pressure for rest of the train is relatively small. Increasing speed does not visibly increase the pressure coefficient, indicating that the pressure increases with the square of the operational speed.

A Study of Aerodynamic Effects of High-Speed Trains through Tunnels

2011 ◽  
Vol 94-96 ◽  
pp. 1663-1667
Author(s):  
Jing Zhao ◽  
Ren Xian Li
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Navier Stokes ◽  
High Speed Train ◽  
Navier Stokes Equations ◽  
Geometry Model ◽  
Flow Geometry ◽  
High Speed Trains ◽  
Set Up ◽  
Numerical Calculation Method

In this paper, the aerodynamic effects of high-speed train passing in tunnels are investigated in numerical calculation method of hydromechanics. According to the actual situation of flow filed when the train through the tunnel, the flow geometry model is set up. The flow problem is described by Navier-Stokes equations of unsteady viscous compressible fluid and k-e two equations turbulent model. Thereby the aerodynamic effects of the train through the tunnel are analyzed comprehensively. The changes of the air pressure in tunnel caused by high-speed train entering into the tunnel are mainly analyzed. In addition, the mechanical characteristics of carriages when two train in the tunnel passing through each other are analyzed.

Unsteady Aerodynamic Characteristics of a High Speed Train with Crosswind

2011 ◽  
Vol 66-68 ◽  
pp. 1878-1882
Author(s):  
Ming Lu Zhang ◽  
Yi Ren Yang ◽  
Chen Guang Fan ◽  
Li Lu
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
High Speed ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Vehicle Speed ◽  
High Speed Train ◽  
Mesh Method

The aerodynamic performances of a high speed train will significant change under the action of the crosswind. Large eddy simulation (LES) was made to solve the flow around a simplified CRH2 high speed train with 250km/h and 350km/h under the influence of a crosswind with 28.4m/s base on the finite volume method and dynamic layering mesh method and three dimensional incompressible Navier-Stokes equations. Wind tunnel experimental method of static train with relative flowing air and dynamic mesh method of moving train were compared. The results of numerical simulation show that the flow field around train is completely different between Wind tunnel experiment and factual running. Many vortices will be produced on the leeside of the train with alternately vehicle bottom and back under the influence of a crosswind. The flow field around train is similar with different vehicle speed.

scholarly journals Investigation of Wall Function Effects on Aerodynamic Characteristics of Turbulent Flow Around a Simplified High-Speed Train

2021 ◽  
Vol 39 (1) ◽  
pp. 309-318
Author(s):  
Alireza Hajipour ◽  
Arash Mirabdolah Lavasani ◽  
Mohammad Eftekhari Yazdi
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
High Speed Train ◽  
Wall Function ◽  
Accurate Analysis ◽  
Navier Stokes Equations ◽  
Wall Functions ◽  
The Government

Modelling of turbulence is a vital issue for flow forecasting which is of great interest for most of engineering applications like flow over planes, movement of pollutants and some industrial processes. Originally, via solving the government equations (Navier-Stokes equations) the flow field can be simulated. With developing PCs and high-performance computers, implementing of Navier-Stokes equations for numerical simulation is increasing. In this research, the effects of some wall functions on aerodynamic and turbulence behavior of air flow around a simplified high-speed train via OpenFOAM software are numerically investigated. In the following, first, the effects of some default and common wall functions of OpenFOAM on the flow and aerodynamic key parameters are analyzed and then, a relatively new wall function called “Enhanced Wall Function” was implemented from ANSYS FLUENT into OpenFOAM and improvement for comprehensive simulation. Variations of flow key parameters such as velocity, pressure distribution and aerodynamic significant components and parameters such as lift, drag and side coefficients under the influence of wall functions changes are illustrated. The results could be used for obtaining more accurate analysis of aerodynamic characteristics of fluid flow around high-speed trains.

Influence of a high-speed train passing through a tunnel on pantograph aerodynamics and pantograph–catenary interaction

2016 ◽  
Vol 231 (2) ◽  
pp. 198-210 ◽  
Author(s):  
Ruiping Li ◽  
Weihua Zhang ◽  
Zhou Ning ◽  
Binbin Liu ◽  
Dong Zou ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Contact Forces ◽  
Blockage Ratio ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Current Collection ◽  
Uplift Forces

Aerodynamics of trains running inside tunnels change more significantly in comparison with open air scenarios. It has been confirmed that the lateral vibration as well as the aerodynamic drag of the trains is increased and the micro-pressure wave is produced at the tunnel exit when the trains are passing through tunnels. The aim of this article is to explore the impact of a high-speed train passing through a tunnel on the pantograph aerodynamics and the dynamic behavior of the pantograph–catenary interaction. The aerodynamic forces acting on the pantograph are investigated thoroughly by extensive numerical simulations as well as systematic field tests. To investigate the effects of the aerodynamic forces of pantograph on the quality of current collection, the numerical simulations of the pantograph–catenary dynamic interaction are conducted with our proposed model, taking into consideration the action of the aerodynamic uplift forces obtained by the numerical simulations on the pantograph. Then, a series of numerical simulations are also carried out to analyze the effects of the train speed and the blockage ratio on the aerodynamic uplift forces of the pantograph, on the contact forces, as well as on the displacement of the contact wire, while the train is passing through a tunnel. The results reveal that compared with the open air scenarios, the aerodynamic drag and uplift forces of the pantograph, the mean value of the contact force and the displacement level of the registration arm can considerably increase as the train runs inside a tunnel. Moreover, the statistical values of the contact forces and the displacement level of the contact wire become larger while the train is passing through the tunnel at different speeds. On the other hand, the quality of current collection decreases with the increasing of the blockage ratio.

Wind-Induced Response of ADSS during the Passage of High-Speed Train

2014 ◽  
Vol 590 ◽  
pp. 69-73
Author(s):  
Yu Wang ◽  
Qiang Gao ◽  
Hai Lin Wang
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Induced Response ◽  
Wind Flow ◽  
High Speed Train ◽  
Navier Stokes Equations ◽  
High Speed Trains

In this paper, the wind-induced response of the ADSS is analyzed when the high-speed trains pass by. The wind flow field of the high-speed train is simulated based on the three-dimensional Reynolds-averaged Navier–Stokes equations, combined with the k-ε turbulence model. The result is shown that the wind load acting on the ADSS is quite low and the stress of the line clamp increases a little.

A Scalable Numerical Method for Simulating Flows Around High-Speed Train Under Crosswind Conditions

2014 ◽  
Vol 15 (4) ◽  
pp. 944-958 ◽  
Author(s):  
Zhengzheng Yan ◽  
Rongliang Chen ◽  
Yubo Zhao ◽  
Xiao-Chuan Cai
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Stokes Equations ◽  
Navier Stokes ◽  
High Speed Train ◽  
Parallel Scalability ◽  
Stabilized Finite Element ◽  
Stabilized Finite Element Method ◽  
Fully Implicit ◽  
High Reynolds

AbstractThis paper presents a parallel Newton-Krylov-Schwarz method for the numerical simulation of unsteady flows at high Reynolds number around a high-speed train under crosswind. With a realistic train geometry, a realistic Reynolds number, and a realistic wind speed, this is a very challenging computational problem. Because of the limited parallel scalability, commercial CFD software is not suitable for supercomputers with a large number of processors. We develop a Newton-Krylov-Schwarz based fully implicit method, and the corresponding parallel software, for the 3D unsteady incompressible Navier-Stokes equations discretized with a stabilized finite element method on very fine unstructured meshes. We test the algorithm and software for flows passing a train modeled after China’s high-speed train CRH380B, and we also compare our results with results obtained from commercial CFD software. Our algorithm shows very good parallel scalability on a supercomputer with over one thousand processors.

scholarly journals CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3934
Author(s):  
Federico Lluesma-Rodríguez ◽  
Temoatzin González ◽  
Sergio Hoyas
Keyword(s):  
Shock Waves ◽  
Power Consumption ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Flow Behavior ◽  
Critical Conditions ◽  
Vehicle Speed ◽  
Blockage Ratio ◽  
The Cost

One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.

On the correlation between aerodynamic drag and wake flow for a generic high-speed train

2021 ◽  
Vol 215 ◽  
pp. 104698
Author(s):  
Xiao-Bai Li ◽  
Xi-Feng Liang ◽  
Zhe Wang ◽  
Xiao-Hui Xiong ◽  
Guang Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Aerodynamic Drag ◽  
Wake Flow ◽  
High Speed Train

Quantitative Analysis of Reynolds and Navier–Stokes Based Modeling Approaches for Isothermal Newtonian Elastohydrodynamic Lubrication

2021 ◽  
Vol 143 (12) ◽  
Author(s):  
Leoluca Scurria ◽  
Tommaso Tamarozzi ◽  
Oleg Voronkov ◽  
Dieter Fauconnier
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Thickness Distribution ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Shear Stresses ◽  
Low Viscosity ◽  
Fluid Film Thickness

Abstract When simulating elastohydrodynamic lubrication, two main approaches are usually followed to predict the pressure and fluid film thickness distribution throughout the contact. The conventional approach relies on the Reynolds equation to describe the thin lubricant film, which is coupled to a Boussinesq description of the linear elastic deformation of the solids. A more accurate, yet a time-consuming method is the use of computational fluid dynamics in which the Navier–Stokes equations describe the flow of the thin lubricant film, coupled to a finite element solver for the description of the local contact deformation. This investigation aims at assessing both methods for different lubrication conditions in different elastohydrodynamic lubrication (EHL) regimes and quantify their differences to understand advantages and limitations of both methods. This investigation shows how the results from both approaches deviate for three scenarios: (1) inertial contributions (Re > 1), i.e., thick films, high speed, and low viscosity; (2) high shear stresses leading to secondary flows; and (3) large deformations of the solids leading to inaccuracies of the Boussinesq equation.

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