An experimental study of the flow over a train in a crosswind at large yaw angles up to 90°

Chiu, T. W.; Squire, L. C.

doi:10.1016/0167-6105(92)90005-u

Cited by 73 publications

(50 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dynamic flow patterns are also in agreement with the experiments by Chiu and Squire [11] that clearly exhibited unsteady vortex shedding at yaw angles ≥ 40 degrees. A whole set of turbulence modeling techniques has been presented by Krajnovic [12] ranging from LES, hybrid RANS-LES to unsteady RANS simulations employing generic train-like vehicles.…”

Section: Introductionsupporting

confidence: 78%

Comparison of Industrial and Scientific CFD Approaches for predicting Cross Wind Stability of the NGT2 Model Train Geometry

Fragner¹,

Weinman²,

Deiterding³

et al. 2015

Int J Railw Tech

View full text Add to dashboard Cite

Safety assessments of cross-wind influence on high-speed train operation require a detailed investigation of the aerodynamic forces acting on a vehicle. European norm 14067-6 permits the derivation of required integral force and moment coefficients by experiments as well as by numerical simulation. Utilizing the DLR's Next Generation Train 2 model geometry, we have performed a case study comparing simulations with varying turbulence modeling assumptions. Because of its relevance for actual design, a focus lies on steady RANS computations, but more expensive unsteady RANS (URANS) and delayed detached eddy simulations (DDES) have also been carried out for comparison. Validation data for the exact same model configuration and moderate Reynolds numbers 250,000 and 450,000 is provided by side wind tunnel experiments. Particular emphasis is laid on simulating a yaw angle of 30• , for which a major vortex system on the leeward side of the train leads to sizeable uncertainties in predicted integral coefficients. At small to intermediate wind angles the flow remains attached and absolute errors in integral quantities decline with decreasing yaw angles. However, a consistent relative difference to the experimental results greater than 10% raises doubts about the general reliability of CFD methods, that are not capable of capturing laminar-turbulent transition, which is observed for scaled models in industry type wind tunnel experiments.1

show abstract

Section: Introductionsupporting

confidence: 78%

Comparison of Industrial and Scientific CFD Approaches for predicting Cross Wind Stability of the NGT2 Model Train Geometry

Fragner¹,

Weinman²,

Deiterding³

et al. 2015

Int J Railw Tech

View full text Add to dashboard Cite

show abstract

“…Since the cross-wind instability is a consequence of the unsteadiness of the flow field around the train, accurate time-dependent solution is necessary. Chiu and Squire (1992) experimentally found that at low yaw angles (up to 40°) the flow is similar to the steady slender body flow, in which pairs of steady line vortices are emerging from the separation lines on the lee-side face to form the wake structures. When the side-wind yaw angle increases above 60°, the flow changes from that associated with a slender body to unsteady vortex shedding.…”

Section: Introductionmentioning

confidence: 99%

“…LES with the same SGS model was successfully used in previous studies to investigate the flow around road vehicles ) and in a crosswind flow (Hemida and Krajnović, 2008). The flow over a real train involves many complexities and the complete modeling of these complexities is generally regarded as impossible (Chiu and Squire, 1992;Chiu, 1995). For this reason, we chose the simplified ICE2 train as the train geometry in our investigations.…”

Section: Introductionmentioning

confidence: 99%

Exploring Flow Structures Around a Simplified ICE2 Train Subjected to A 30° Side Wind Using LES

Hemida

Krajnović

2009

Engineering Applications of Computational Fluid Mechanics

View full text Add to dashboard Cite

Large-eddy simulation (LES) is conducted to investigate the flow around a simplified ICE2 train under side wind conditions at 30° yaw angle. The Reynolds number based on the height of the train and the free stream velocity is 2×10 5 . Two computations on two different meshes with different numbers of nodes are made to check the effect of the mesh resolution on the results. The fine and the coarse meshes give similar results meaning that the results are mesh independent. The results are also verified against available experimental data. Good agreement is obtained between the LES results and the experimental data. The LES results show that two flow regimes exist in the wake. The first flow regime consists of steady vortex lines in the upper part of the wake flow. It changes into unsteady shedding after a distance of about five train heights from their onset on the surface of the train. The second flow regime is the unsteady movement of the lower part of the wake vortices. They attach and detach from the surface of the train in a regular fashion. The time-averaged flow and the instantaneous flow around the ICE2 train at 30° yaw angle are explored.

show abstract

“…Example of researchers who have experimentally measured the train aerodynamics are Baker et al, 5 Chiu and Squire, 6 Copley, 7 Suzuki et al 8 and Hoppmann. 9 Their investigations focussed on the aerodynamic characteristics such as drag, lift and side force together with the measurement of flow characteristics along the train.…”

Section: Introductionmentioning

confidence: 99%

“…9 Their investigations focussed on the aerodynamic characteristics such as drag, lift and side force together with the measurement of flow characteristics along the train. Chiu et al 6 investigated the effect of yaw angle on the formation of vorticies through full scale wind tunnel experiments. They found that at yaw angles up to 45…”

Section: Introductionmentioning

confidence: 99%

Flow modelling and noise generation of interacting prisms

Prime

Moreau

Doolan

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

View full text Add to dashboard Cite

Noise generation is a significant issue for High-Speed Trains (HSTs), and as speeds increase aerodynamically generated noise becomes the dominant noise source. In this article, the effect of nose shape, carriage separation and yaw angle on the aerodynamics and noise generation are analysed using two prisms, representing a HST model. The aerodynamics are modelled using Computation Fluid Dynamics (CFD), and the flow velocity and turbulence intensity in various positions in the wake are compared with experimental hotwire data measured in the Anechoic Wind Tunnel (AWT) at The University of Adelaide, with good agreement. Finally, acoustic beamforming images of the noise generated by the interacting prisms measured in the AWT are presented. The acoustic results show that a blunt nose tends to increase noise at lower frequencies significantly, while increasing prism separation tends to increase noise over most frequencies, but most significantly at midfrequencies, and increasing yaw angle increases noise across all frequencies. Beamforming results show that at lower frequencies, this noise tends to be generated at the leading and trailing edges, while at higher frequencies the noise tends to be generated in the carriage gap.

show abstract

An experimental study of the flow over a train in a crosswind at large yaw angles up to 90°

Cited by 73 publications

References 6 publications

Comparison of Industrial and Scientific CFD Approaches for predicting Cross Wind Stability of the NGT2 Model Train Geometry

Comparison of Industrial and Scientific CFD Approaches for predicting Cross Wind Stability of the NGT2 Model Train Geometry

Exploring Flow Structures Around a Simplified ICE2 Train Subjected to A 30° Side Wind Using LES

Flow modelling and noise generation of interacting prisms

Contact Info

Product

Resources

About