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Detached-Eddy Simulations of the Effects of Different Wind Gust Models on the Unsteady Aerodynamics of Road Vehicles
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aerodynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aeroacoustics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.ORCID iD: 0000-0002-9061-4174
2010 (English)In: ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels (FEDSM2010), 2010, 2605-2614 p.Conference paper (Refereed)
Abstract [en]

Therelative flexibility of nowadays simulation techniques offers an alternative wayto experiments in order to investigate unsteady crosswind aerodynamics inan industrial framework. In this study, time-accurate simulations, Detached-Eddy Simulations(DES), are used to simulate the flow around a simplevehicle shape, the so-called Windsor model. The ReL of thecorresponding flow case is 2.0 · 106. The influence ofdifferent deterministic models of wind gusts on the aerodynamic loadsand moments are studied. The wind gusts are varied inthe stream-wise and the vertical direction. The magnitude of thegusts models corresponds to a yaw angle of 20°. Theaerodynamic loads calculated show a large excess of drag coupledwith a reduction of the pitch moment. In addition, althoughthe side force has a smooth variation in the gust,overshoots up to 18% higher than the steady value ofyaw moment are also observed.

Place, publisher, year, edition, pages
2010. 2605-2614 p.
National Category
Vehicle Engineering Fluid Mechanics and Acoustics
URN: urn:nbn:se:kth:diva-50487DOI: 10.1115/FEDSM-ICNMM2010-30454ISI: 000307365700290ScopusID: 2-s2.0-80055016238ISBN: 978-0-7918-4948-4OAI: diva2:462147
3rd Joint US-European Fluids Engineering Division Summer Meeting

QC 20111206

Available from: 2011-12-06 Created: 2011-12-06 Last updated: 2013-06-11Bibliographically approved
In thesis
1. Aerodynamics simulations of ground vehicles in unsteady crosswind
Open this publication in new window or tab >>Aerodynamics simulations of ground vehicles in unsteady crosswind
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Ground vehicles, both on roads or on rail, are sensitive to crosswinds and the handling, travelling speeds or in some cases, safety can be affected. Full modelling of the crosswind stability of a vehicle is a demanding task as the nature of the disturbance, the wind gust, is complex and the aerodynamics, vehicle dynamics and driver reactions interact with each other. 

One of the objectives of this thesis, is to assess the aerodynamic response of simplified ground vehicles under sudden strong crosswind disturbances by using an advanced turbulence model. In the aerodynamic simulations, time-dependant boundary data have been used to introduce a deterministic wind gust model into the computational domain. 

This thesis covers the implementation of such gust models into Detached-Eddy Simulations (DES) and assesses the overall accuracy. Different type of grids, numerical setups and refinements are considered. Although the overall use of DES is seen suitable, further investigations can be foreseen on more challenging geometries. 

Two families of vehicle models have been studied. The first one, a box-like geometry, has been used to characterize the influence of the radius of curvature and benefited from unsteady experimental data for comparison. The second one, the Windsor model, has been used to understand the impact of the different rear designs. Noticeably, the different geometries tested have exhibited strong transients in the loads that can not be represented in pure steady crosswind conditions.

The static coupling between aerodynamics and vehicle dynamics simulations enhances the comparisons of the aerodynamic designs. Also, it shows that the motion of the centre of pressure with respect the locations of the centre of gravity and the neutral steer point, is of prime interest to design vehicles that are less crosswind sensitive. Recommendations on the future work on crosswind sensitivity for ground vehicles are proposed at the end of this thesis.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. xx, 67 p.
Trita-AVE, ISSN 1651-7660 ; 2011:82
Detached-Eddy Simulations; Crosswind; Aerodynamics;
National Category
Aerospace Engineering Vehicle Engineering
urn:nbn:se:kth:diva-50242 (URN)978-91-7501-196-7 (ISBN)
Public defence
2011-12-16, E1, Lindstedsvägen 3, KTH, Stockholm, 14:00 (English)
crosswind stability and unsteady aerodynamics

QC 20111206

Available from: 2011-12-06 Created: 2011-12-03 Last updated: 2013-06-25Bibliographically approved

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