Aerodynamic characteristics of high speed train under turbulent cross winds: A numerical investigation using unsteady-RANS method

Biadgo, Asress Mulugeta; Simonović, Aleksandar; Svorcan, Jelena; Stupar, Slobodan

doi:10.5937/fmet1401010b

Cited by 20 publications

(15 citation statements)

References 12 publications

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“…where µ represnts the viscocity of the fluid and ρu i u j represents the Reynolds stress. According to [42], the turbulent stress tensor in the nonlinear term in Equation (3) can be written as shown in Equation 4.…”

Section: Computational Modelingmentioning

confidence: 99%

Mitigating the Piston Effect in High-Speed Hyperloop Transportation: A Study on the Use of Aerofoils

Bose

Viswanathan

2021

Energies

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The Hyperloop is a concept for the high-speed ground transportation of passengers traveling in pods at transonic speeds in a partially evacuated tube. It consists of a low-pressure tube with capsules traveling at both low and high speeds throughout the length of the tube. When a high-speed system travels through a low-pressure tube with a constrained diameter such as in the case of the Hyperloop, it becomes an aerodynamically challenging problem. Airflow tends to get choked at the constrained areas around the pod, creating a high-pressure region at the front of the pod, a phenomenon referred to as the “piston effect.” Papers exploring potential solutions for the piston effect are scarce. In this study, using the Reynolds-Average Navier–Stokes (RANS) technique for three-dimensional computational analysis, the aerodynamic performance of a Hyperloop pod inside a vacuum tube is studied. Further, aerofoil-shaped fins are added to the aeroshell as a potential way to mitigate the piston effect. The results show that the addition of fins helps in reducing the drag and eddy currents while providing a positive lift to the pod. Further, these fins are found to be effective in reducing the pressure build-up at the front of the pod.

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Section: Computational Modelingmentioning

confidence: 99%

Mitigating the Piston Effect in High-Speed Hyperloop Transportation: A Study on the Use of Aerofoils

Bose

Viswanathan

2021

Energies

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“…As for airflow and aerodynamics simulation, three different CFD techniques are employed, Reynolds-Averaged Navier-Stokes (RANS), unsteady RANS (URANS), and Large Eddy Simulation (LES) [30][31][32][33][34][35]. The Reynolds-Averaged Navier-Stokes (RANS) solves time-averaged steady-state Navier-Stokes equations while the unsteady RANS numerically solves unsteady Navier-Stokes equation [36][37][38]. On the other hand, the Large Eddy Simulation (LES) solves space, position, area, and size for averaged Navier-Stokes equations spatially.…”

Section: Computational Fluid Dynamics (Cfd)mentioning

confidence: 99%

A Review of Aerodynamics Influence on Various Car Model Geometry through CFD Techniques

Kamal

Ishak

Darlis

et al. 2021

ARFMTS

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The aerodynamic characteristics of a vehicle play a vital role in steering stability, performance, comfort, and safety of a car. The fuel efficiency of a vehicle is determined by the performance of the internal combustion engine and the aerodynamic design of the body. One of the most important aspects of automobile design is aerodynamic styling. A vehicle with low drag resistance provides advantages in terms of cost and efficiency. This article will review design characteristics and implementation of various specific reference models on drag issues using Computational Fluid Dynamics (CFD) techniques. The benefits and limitations of these models are analysed, and the validity of results in developing guidelines to improve the performance and stability of cars are described. This review paper covers significant studies that utilise the CFD model and simulation on a simplified vehicle model using various turbulence models to generate drag coefficient. Characteristics and impacts of various vehicle design models with and without external factors such as side mirrors and door handles are also discussed. Results obtained from the research focuses on the physics flow structures such as static pressure contours, are presented for the three types of car model geometry. The simplified generic models are more efficient and advocated to apply compared to the specific model geometry based on the result acquired by the latest studies. Simplified generic models are preferred due to their cost-effectiveness, procurement of optimum time, and better simulation effects. Moreover, the study also demonstrates the importance of having a car with suitable turbulence models that are appropriate to be applied for simulations in terms of its applicability, time effectiveness, and cost.

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“…General guidelines on the distances between the inlet and the vehicle as well as the vehicle with the outlet follow the proposed length parameter based on a previous investigation made. The computational domain is based on the reference [25,35,36] which specify the appropriate distances from the inlet to train model is equal to 8H and the distance from train model to the outlet is equal to 21H. Figure 4 shows the placement of the train model travelling on the flat ground case.…”

Section: Computational Domainmentioning

confidence: 99%

Numerical Analysis on the Crosswind Influence Around a Generic Train Moving on Different Bridge Configurations

Ishak

Maruai

Sakri

et al. 2021

ARFMTS

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In this article, a numerical approach is applied to study the flow regimes surround a generic train model travelling on different bridge configurations under the influence of crosswind. The bridge is varies based on the different geometry of the bridge girder. The crosswind flow angle (Ψ) is varied from 0° to 90°. The incompressible flow around the train was resolved by utilizing the Reynolds-averaged Navier-Stokes (RANS) equations combined with the SST k-ω turbulence model. The Reynolds number used, based on the height of the train and the freestream velocity, is 3.7 × 105. In the results, it was found that variations of the crosswind flow angles produced different flow regimes. Two unique flow regimes appear, representing (i) slender body flow behaviour at a smaller range of Ψ (i.e. Ψ ≤ 45°) and (ii) bluff body flow behaviour at a higher range of Ψ (i.e. Ψ ≥ 60°). As the geometries of the bridge girder were varied, the bridge with the wedge girder showed the worst aerodynamic properties with both important aerodynamic loads (i.e. side force and rolling moment), followed by the triangular girder and the rectangular girder. This was due to the flow separation on the windward side and flow structure formation on the leeward side, both of which are majorly influenced by the flow that moved from the top and below of the bridge structures.

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Aerodynamic characteristics of high speed train under turbulent cross winds: A numerical investigation using unsteady-RANS method

Cited by 20 publications

References 12 publications

Mitigating the Piston Effect in High-Speed Hyperloop Transportation: A Study on the Use of Aerofoils

Mitigating the Piston Effect in High-Speed Hyperloop Transportation: A Study on the Use of Aerofoils

A Review of Aerodynamics Influence on Various Car Model Geometry through CFD Techniques

Numerical Analysis on the Crosswind Influence Around a Generic Train Moving on Different Bridge Configurations

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