The Effect of Backlight Aspect Ratio on Vortex and Base Drag for a Simple Car-Like Shape

Howell, Jeff; Good, Geoff Le

doi:10.4271/2008-01-0737

Cited by 26 publications

(28 citation statements)

References 4 publications

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“…The pressures show far greater suction at the outer edge of the top slant than for any other configuration, indicating the presence of 3D slant edge vortices. While these will generally induce a local downwash over the slant near the vortex structure, and encourage reattachment of the flow, they are also known to create induced drag [18,21]. Due to the short slant length the vortices will remain weaker than in a traditional fastback flow field and the influence of these structures will be localized.…”

Section: Top and Bottom Edge Tapermentioning

confidence: 99%

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Influence of Short Rear End tapers on the Base Pressure of a Simplified Vehicle.

Perry

Passmore

Finney

2015

SAE Int. J. Passeng. Cars - Mech. Syst.

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Author, co-author (Do NOT enter this information. It will be pulled from participant tab in MyTechZone)Affiliation (Do NOT enter this information. It will be pulled from participant tab in MyTechZone) AbstractThis paper looks into the effect on base pressure of applying a high aspect ratio chamfer to all edges of a simplified squareback model (the Windsor model). The effects are investigated using force and moment measurements along with surface pressure measurements on the slanted surface and vertical base. The work forms part of a larger study to develop understanding of the mechanisms that influence overall base pressure and hence the resulting aerodynamic drag.A short slant (approx. 4% of model length) was applied to the trailing edges of the simplified vehicle model, representing the small rear end optimisation typical of many real vehicle geometries. Two experiments were performed: the first applied a chamfer at varying angles to the top and bottom edges; the second test looked at the same chamfer angle applied to the sides of the model geometry while the top and bottom angle remained square. The changes in drag are discussed and explained in the context of the base pressures and area weighted pressure coefficients.

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Section: Top and Bottom Edge Tapermentioning

confidence: 99%

“…The Windsor Model, as used in [17,18] was used in this work, its general dimensions are shown in Figure 2. The model is equivalent to an approximately quarter scale road car and gives a tunnel blockage of 4.4% in the 2.5m 2 working section.…”

Section: The Modelmentioning

confidence: 99%

Influence of Short Rear End tapers on the Base Pressure of a Simplified Vehicle.

Perry

Passmore

Finney

2015

SAE Int. J. Passeng. Cars - Mech. Syst.

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“…A quarter scale Windsor Model, Figure 1, as used in [4,7,8,14,15] was used for this work. The model is constructed of a machinable model board and gives a blockage ratio of 4.4% in the 2.5m 2 working section.…”

Section: Modelmentioning

confidence: 99%

The Study of a Bi-Stable Wake Region of a Generic Squareback Vehicle using Tomographic PIV

Perry¹,

Almond²,

Passmore³

et al. 2016

SAE Int. J. Passeng. Cars - Mech. Syst.

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“…The model details have been well documented previously; see for example Howell and Le Good, [15]. The model is 1.044m long, 0.39m wide and 0.29m high, and the overall dimensions represent an approximately quarter scale small hatchback car.…”

Section: Modelmentioning

confidence: 90%

“…The experiment was conducted with a fixed roof taper angle of 15° and the taper length was varied over a similar range to that in the main experiment. This data was supplemented with earlier measurements on the same model by Howell and Le Good, [15], investigating the effects of variable backlight aspect ratio and Littlewood and Passmore, [17], exploring the effect of a small roof trailing edge chamfer. The latter study was carried out using the Loughborough University wind tunnel, while the former investigation was done using the MIRA Model Wind Tunnel (MWT).…”

Section: Discussionmentioning

confidence: 99%

Aerodynamic Drag Reduction on a Simple Car-Like Shape with Rear Upper Body Taper

Howell¹,

Passmore²,

Tuplin³

2013

SAE Int. J. Passeng. Cars - Mech. Syst.

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Various techniques to reduce the aerodynamic drag of bluff bodies through the mechanism of base pressure recovery have been investigated. These include, for example, boat-tailing, base cavities and base bleed. In this study a simple body representing a car shape is modified to include tapering of the rear upper body on both roof and sides. The effects of taper angle and taper length on drag and lift characteristics are investigated. It is shown that a significant drag reduction can be obtained with moderate taper angles. An unexpected feature is a drag rise at a particular taper length. Pressure data obtained on the rear surfaces and some wake flow visualisation using PIV are presented.

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The Effect of Backlight Aspect Ratio on Vortex and Base Drag for a Simple Car-Like Shape

Cited by 26 publications

References 4 publications

Influence of Short Rear End tapers on the Base Pressure of a Simplified Vehicle.

Influence of Short Rear End tapers on the Base Pressure of a Simplified Vehicle.

The Study of a Bi-Stable Wake Region of a Generic Squareback Vehicle using Tomographic PIV

Aerodynamic Drag Reduction on a Simple Car-Like Shape with Rear Upper Body Taper

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