Adaptive Base-Flaps Under Variable Cross-Wind

Cruz, J. M. García de la; Brackston, Rowan D.; Morrison, J. F.

doi:10.4271/2017-01-7000

Cited by 11 publications

(12 citation statements)

References 11 publications

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“…Additionally, they tested tapers only on the upper 50% of the Windsor body equipped with wheels, showing a greater total drag reduction than the full height tapering. This was attributed to longitudinal vortices re-symmetrising the wake, consistent with the literature that reports a more symmetric wake as resulting in lower drag [18][19][20], but no pressure or flow field measurements were presented to confirm this.…”

Section: Introductionsupporting

confidence: 74%

Parametric Study of Reduced Span Side Tapering on a Simplified Model with Wheels

Varney

Passmore

Swakeen

et al. 2020

SAE Technical Paper Series

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Many modern vehicles have blunt rear end geometries for design aesthetics and practicality; however, such vehicles are potentially high drag. The application of tapering; typically applied to an entire edge of the base of the geometry is widely reported as a means of reducing drag, but in many cases, this is not practical on real vehicles. In this study side tapers are applied to only part of the side edge of a simplified automotive geometry, to show the effects of practical implementations of tapers.The paper reports on a parametric study undertaken in Loughborough University's Large Wind Tunnel with the ¼ scale Windsor model equipped with wheels. The aerodynamic effect of implementing partial side edge tapers is assessed from a full height taper to a 25% taper in both an upper and lower body configuration. These were investigated using force and moment coefficients, pressure measurements and planar particle image velocimetry (PIV). These geometries showed that the drag reductions are maximised with a 50% span, generating a vertically symmetric wake and less taper drag contribution when compared to a full span taper.

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Section: Introductionsupporting

confidence: 74%

Parametric Study of Reduced Span Side Tapering on a Simplified Model with Wheels

Varney

Passmore

Swakeen

et al. 2020

SAE Technical Paper Series

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“…2017; Bonnavion & Cadot 2018), with base boat-tailing (Perry, Passmore & Finney 2015; Pavia, Passmore & Gaylard 2016; Bonnavion & Cadot 2019) or actively with flaps (Brackston et al. 2016; García de la Cruz, Brackston & Morrison 2017; Brackston, Wynn & Morrison 2018). Overall, three main effects have been observed.…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis of the effect of local base blowing on three-dimensional wake modes

Lorite-Díez

Jiménez-González

Pastur³

et al. 2019

J. Fluid Mech.

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“…The bottom of the cavity is aligned tangent at the same height as the flat floor. The cavity provides additional tapering resulting in an approximately 15 • taper on the sides and roof with no tapering on the bottom which is similar to other geometries with base cavities at yaw (Lorite-Díez et al 2020;Garcia de la Cruz et al 2017;Urquhart et al 2020aUrquhart et al , 2018. Figure 1b shows the pressure tap locations on the base and the clockwise flap naming convention.…”

Section: Test Object With Flapsmentioning

confidence: 73%

“…Bluff body wakes continue to be an actively researched area primarily focused on wake flow without yaw, however, several studies at yaw exist (Howell 2015;Windsor 2014;Cooper 2003;Sterken et al 2014a;Favre 2011;Pfeiffer and King 2018;Li et al 2019;Lorite-Díez et al 2020). The literature is often limited to symmetric designs, although asymmetric tapering was investigated by Garcia de la Cruz et al (2017) and Varney et al (2018), showing drag reductions over symmetric designs when the windward side was tapered more than the leeward side. Similar results were found by Li et al (2019) who applied pulsed jets to the sides of an Ahmed body at yaw and found a reduction in drag by deviating the windward shear layer towards the leeward side.…”

mentioning

confidence: 99%

The benefits of green horizontal networks: Lessons learned from sharing charging infrastructure for electric freight vehicles

Melander

Wallström²

2022

Bus Strat Env

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Regulations to reduce greenhouse gas emissions of passenger vehicles are becoming increasingly stringent. The aerodynamic drag is a major contributor to the vehicle's total energy consumption where a large portion is attributed to the base wake. This paper optimises the angles of small trailing edge flaps on a base cavity of a full-scale sports utility vehicle placed in a wind tunnel. The trailing edge flaps are controlled using servos mounted inside the cavity. The flap angles are optimised using a surrogate model based optimisation algorithm with the objective of reducing the aerodynamic drag at different yaw angles and to create a yaw-insensitive geometry by considering several weighted yaw angles to form the driving cycle averaged drag. Low drag designs are further investigated using base pressures and wake measurements. The results show that the base pressures are symmetrised by reducing the crossflow in the wake. As the model is yawed the wake becomes increasingly downwash dominated by a large rotating windward structure which is reduced by the optimised flaps. The cycle averaged drag optimised design has a smaller increase in drag when yawed compared to a design optimised without considering yaw.

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Adaptive Base-Flaps Under Variable Cross-Wind

Cited by 11 publications

References 11 publications

Parametric Study of Reduced Span Side Tapering on a Simplified Model with Wheels

Parametric Study of Reduced Span Side Tapering on a Simplified Model with Wheels

Experimental analysis of the effect of local base blowing on three-dimensional wake modes

The benefits of green horizontal networks: Lessons learned from sharing charging infrastructure for electric freight vehicles

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