An Assessment of Detached-Eddy Simulations of Unsteady Crosswind Aerodynamics of Road Vehicles

Favre, Tristan; Efraimsson, Gunilla

doi:10.1007/s10494-011-9333-4

Cited by 33 publications

(22 citation statements)

References 32 publications

(51 reference statements)

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“…With the advantages of RANS and LES, detached-eddy simulation (DES) method has been applied to simulate the transient flow field around trains in recent years. Computational results are basically consistent with experimental results [21][22][23]. This paper combined the aerodynamics of the high-speed train with system dynamics to study the transient aerodynamic response and safety of the high-speed train under cross winds.…”

Section: Introductionsupporting

confidence: 76%

Numerical simulation on the aerodynamic performance of the high-speed train under crosswinds

Yang¹,

Zhang²,

Li³

et al. 2018

J. vibroeng.

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With the continuously increased speed of the high-speed train, the lateral aerodynamic performance of high-speed trains has attracted more and more attention. Under strong crosswinds, the aerodynamic performance of trains deteriorate and air drag, lift and lateral forces borne by trains quickly increase, which has an impact on the lateral stability of trains and even leads to train derailment. This paper adopted computational fluid dynamics theory to establish an aerodynamic model for a high-speed train, computed aerodynamic forces and moments acting on the high-speed train and obtained the unsteady flow field of the high-speed train. In the meanwhile, this paper combined with multi-body system dynamics theory to establish a system dynamics model for the train and analyzed the safe aerodynamic performance of the high-speed train under cross winds. Computational results showed: Under cross winds, the aerodynamic performance of the highspeed train had a random fluctuation. When wind direction angle was 90°, aerodynamic forces (drag, lift and lateral forces) and moments (overturning moment, shaking moment and nodding moment) borne by the high-speed train were the largest; train speed was a main factor affecting the size of positive pressures of train and cross wind velocity had no obvious impacts on the positive and negative pressures of train body; the aerodynamic forces and moments of the high-speed train had a random fluctuation within a certain range with time; the frequency for the peak value of power spectral density of lateral forces of head train was within 25 Hz and the peak value of power spectral density was the largest when the main frequency was 1.6 Hz; the frequency for the peak value of power spectral density of overturning moment of head train was within 20 Hz and main frequency was 0.57 Hz. When the cross wind speed was 15 m/s, all safety indexes of the high-speed train running at the speed of 250 km/h were within the range of limited values and satisfied design requirements. Aerodynamic performance of the high-speed train with the suction chamber under the cross wind was computed and compared with original results. Aerodynamic force and force moments of the high-speed train under cross wind will be reduced obviously and running safety of the high-speed train can be improved through application of the suction chamber.

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Section: Introductionsupporting

confidence: 76%

Numerical simulation on the aerodynamic performance of the high-speed train under crosswinds

Yang¹,

Zhang²,

Li³

et al. 2018

J. vibroeng.

View full text Add to dashboard Cite

show abstract

“…DES (detached eddy simulation) is a representative hybrid RANS-LES method that was originally proposed by Spalart et al (1997). With fast development in turbulence model, the DES is becoming a promising method in modelling separated flows at high Reynolds numbers, showing a good prediction in the external flow around ground transport vehicles (Favre and Efraimsson, 2011;Guilmineau et al, 2013;Flynn et al, 2014;Morden et al, 2015;Huang et al, 2016;Niu et al, 2017;Zhu et al, 2017;Zhang et al, 2016Zhang et al, , 2017Zhang et al, and 2018a.…”

Section: Methodsmentioning

confidence: 99%

Effect of Two Bogie Cavity Configurations on the Underbody Flow and Near Wake Structures of a High-Speed Train

Zhang

et al. 2019

JAFM

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A time-dependent simulation method, DES (detached eddy simulation), combined with Realizable k-ε turbulence model, has been adopted to study the underbody flow and near wake structures of a high-speed train with two bogie cavity configurations laid on the stationary ground. The numerical data, including timeaveraged aerodynamic drag forces and pressure coefficients, were compared with experimental results from previous wind tunnel tests. A detail comparison of the instantaneous flow structures, mean velocity vector contours, velocity and pressure profiles under the train bottom in the symmetry plane and velocity contours overlaid with streamlines in the wake has been conducted in the two configurations. Also the aerodynamic drag coefficients for the two cases are discussed herein. The two cases show that the bogie cavity configurations contribute to the differences of velocity and pressure distributions in each bogie region, as well as the complex vortex structures around the bogie regions. Compared to the inclined bogie cavity configuration, the train with straight plates experiences a lower drag force by 2.8% for a three-car model in the stationary ground. Thus, an effective simplification criterion for the train model will contribute to an accurate prediction of forces of trains in simulations.

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“…As a new research tool, the DES method has been widely used to predict the aerodynamic forces and high-Reynolds number separated flows around ground transport vehicles (Favre et al 2011, Guilmineau et al 2011, Miao and Gao 2012, Flynn et al 2014. This model, which was first proposed by Spalart and Allmaras (1997), is a hybrid Reynolds-averaged Navier-Stokes-Large-Eddy Simulation (RANS-LES) method.…”

Section: Methodsmentioning

confidence: 99%

Numerical Simulation with a DES Approach for a High-Speed Train Subjected to the Crosswind

Zhang

Xiong

et al. 2017

JAFM

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A Detached Eddy Simulation (DES) method based on the SST k-ω turbulence model was used to investigate the instantaneous and time-averaged flow characteristics around the train with a slender body and high Reynolds number subjected to strong crosswinds. The evolution trends of multi-scale coherent vortex structures in the leeward side were studied. These pressure oscillation characteristics of monitoring points on the train surfaces were discussed. Time-averaged pressure and aerodynamic loads on each part of the train were analyzed inhere. Also, the overturning moment coefficients were compared with the experimental data. The results show that the flow fields around the train present significant unsteady characteristics. Lots of vortex structures with different intensities, spatial geometrical scales, accompanied by a time change, appear in the leeward side of the train, in the wake of the tail car and below the bottom of the train. The oscillation characteristics of the flow field around the train directly affect the pressure change on the train surfaces, thereby affecting the aerodynamic loads of the train. The loads of each car fluctuate around some certain mean values, while the positive peak values can be higher than the mean ones by up to 34%. The load contributions of different parts to the total of the train are also obtained. According to it, to improve the crosswind stability of the high-speed train, much more attention should be paid on the aerodynamic shape design of the streamlined head and cross section. In addition, this work shows that the DES approach can give a better prediction of vortex structures in the wake compared with the RANS solution.

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An Assessment of Detached-Eddy Simulations of Unsteady Crosswind Aerodynamics of Road Vehicles

Cited by 33 publications

References 32 publications

Numerical simulation on the aerodynamic performance of the high-speed train under crosswinds

Numerical simulation on the aerodynamic performance of the high-speed train under crosswinds

Effect of Two Bogie Cavity Configurations on the Underbody Flow and Near Wake Structures of a High-Speed Train

Numerical Simulation with a DES Approach for a High-Speed Train Subjected to the Crosswind

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