The Wingtip Vortex of a Dimpled Wing With an Endplate

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Christopher C. Beves ◽  
Tracie J. Barber
Keyword(s):  
Boundary Layer ◽  
Laser Doppler Anemometry ◽  
Flow Characteristics ◽  
Ground Effect ◽  
Laser Doppler ◽  
Vortex Generators ◽  
Large Region ◽  
Wingtip Vortex ◽  
High Turbulence

Dimples used as sub-boundary layer vortex generators have been shown to reduce wake size at large angles of incidence. The effect these dimples have on wingtip vortices with an endplate is measured via laser Doppler anemometry (LDA) on an inverted Tyrrell026 airfoil (ReC = 0.5 × 105 and chord = 0.075 m) in ground effect in order to determine the flow characteristics for this configuration and to see if previous measurements were performed in a thinner part of the wake due to any potential wake waviness. The strength of the wingtip vortex for the dimpled wing is 10% higher than the “clean” wing immediately downstream. The clean wing has large region of high turbulence throughout the wake, and the dimples reduce this by 50%. The net result is that dimples drastically improve the flow in the wake of the wing and endplate.

Aerodynamic Investigation of a Passive Secondary Jet Exciting a Separation Bubble for a Blunt Flat Plate

2015 ◽  
Author(s):  
Christian Helcig ◽  
Stefan aus der Wiesche ◽  
Stephan Uhkoetter
Keyword(s):  
Boundary Layer ◽  
Laser Doppler Anemometry ◽  
Separation Bubble ◽  
Flow Characteristics ◽  
Numerical Procedure ◽  
Large Eddy Simulations ◽  
Reattachment Length ◽  
Large Eddy ◽  
Low Speed Wind Tunnel ◽  
Aerodynamic Investigation

The aim of this study is to examine the influence of passive jets interacting with the separation region of the flow around a blunt plate. Experimental and numerical analysis are used to measure the velocity within the separation and reattachment region of the blunt plate with different passive jet configurations. A blunt plate was placed in a low speed wind tunnel to conduct Laser-Doppler anemometry (LDA) measurements at Re = 2.06 × 104. For the numerical procedure a dynamical sub-grid model for Large Eddy Simulations (LES) was used. For all configurations the flow characteristics such as the reattachment length were determined to characterize the boundary layer. The passive jets showed a strong influence by interacting with the boundary layer of the blunt plate.

Flow Physics of a Race Car Wing With Vortex Generators in Ground Effect

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Yuichi Kuya ◽  
Kenji Takeda ◽  
Xin Zhang ◽  
Scott Beeton ◽  
Ted Pandaleon
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Vortex Generator ◽  
Ground Effect ◽  
Surface Flow ◽  
Vortex Generators ◽  
Separation Control ◽  
Race Car ◽  
Horseshoe Vortices ◽  
Large Scale Vortex

This paper experimentally investigates the use of vortex generators for separation control on an inverted wing in ground effect using off-surface flow measurements and surface flow visualization. A typical racing car wing geometry is tested in a rolling road wind tunnel over a wide range of incidences and ride heights. Rectangular vane type of sub-boundary layer and large-scale vortex generators are attached to the suction surface, comprising counter-rotating and corotating configurations. The effects of both device height and spacing are examined. The counter-rotating sub-boundary layer vortex generators and counter-rotating large-scale vortex generators suppress the flow separation at the center of each device pair, while the counter-rotating large-scale vortex generators induce horseshoe vortices between each device where the flow is separated. The corotating sub-boundary layer vortex generators tested here show little evidence of separation control. Increasing the spacing of the counter-rotating sublayer vortex generator induces significant horseshoe vortices, comparable to those seen in the counter-rotating large-scale vortex generator case. Wake surveys show significant spanwise variance behind the wing equipped with the counter-rotating large-scale vortex generators, while the counter-rotating sub-boundary layer vortex generator configuration shows a relatively small variance in the spanwise direction. The flow characteristics revealed here suggest that counter-rotating sub-boundary layer vortex generators can provide effective separation control for race car wings in ground effect.

Aerofoil flow separation suppression using dimples

2011 ◽  
Vol 115 (1168) ◽  
pp. 335-344 ◽  
Author(s):  
C. C. Beves ◽  
T. J. Barber
Keyword(s):  
Heat Transfer ◽  
Flow Separation ◽  
Laser Doppler Anemometry ◽  
Ground Effect ◽  
Separated Flows ◽  
Vortex Generators ◽  
Experimental Measurements ◽  
Velocity Deficit ◽  
Flow Mixing ◽  
Positive Effect

AbstractFlow separation is a source of aerodynamic inefficiency, by using vortex generators flow separation can be controlled. This is of particular benefit to flows around bodies which are susceptible to separated flows, such as bodies in ground effect. Previous studies on the ability of dimples to produce vortices for flow mixing concerned heat transfer applications. Experimental measurements using Laser Doppler Anemometry (LDA) were taken in the wake of the Tyrrell026 aerofoil (Rec= 0·5 × 105) with a dimple array machined in the surface. Results for a dimple array of three rows placed forward ofx/c= 0·23 with 1·5Ddimple to dimple spacing, showed significant flow recovery in the wake. The velocity deficit ofu/Uo,min= −0·1 recovered tou/Uo,min = 0·3 with the dimple array and the size of the wake reduced by 50%; at α = 10°,h/c= 0·313. The positive effect of the dimple array on the wing reduced as the wing was brought closer to the ground.

scholarly journals Investigation of the flow inside an urban canopy immersed into an atmospheric boundary layer using laser Doppler anemometry

2018 ◽  
Vol 59 (5) ◽  
Author(s):  
Sophie Herpin ◽  
Laurent Perret ◽  
Romain Mathis ◽  
Christian Tanguy ◽  
Jean-Jacques Lasserre
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Laser Doppler Anemometry ◽  
Urban Canopy ◽  
Laser Doppler
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