Vortex Generator Installation Drag on an Airplane Near Its Cruise Condition

Aerodynamic characteristics of two-and three-dimensional NASA common research model (2D-CRM and 3D-CRM) with co-rotating vortex generators (VGs) were investigated to clarify the influence of the three-dimensionality of the wings on the VGs effect. The base height of the VGs was 1.5 times of the boundary layer thickness at the VGs location. The direction of the VGs on the 3D-CRM was toe-out which meant the leading edge of the VGs turned to the wing tip. The Mach numbers in the 2D-and 3D-CRM experiment were 0.74 and 0.85 considering the sweepback angle of the 3D-CRM. The lift coefficient and the oil flow visualization showed that the effect of the VGs on the 3D-CRM was much larger than that on the 2D-CRM. From the comparison between the experiments and the CFD results, we concluded that the difference between 2D-and 3D-CRM was mainly caused by the crossflow due to the swept wing. The cross-flow enhances the effect of the co-rotating toe-out VGs on the swept wings. The installation drag of VGs was also investigated for the 3D-CRM and validated an empirical method to estimate the installation drag. At C L conditions below the design C L = 0.5, the VGs increased the total drag as expected, while at C L conditions above the design C L , the VGs decreased the total drag because the VGs suppressed the separation and the effect exceeded the installation drag of the VGs. Nomenclature AoA = angle of attack AR = aspect ratio of vortex generator defined by Eq. (11) Av = angle of vortex generators

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“…The installation drag of VGs (C DVG -C DClean ) was estimated using the method in Ref. 27. The drag was estimated by the next equations.…”

Section: Penalty Of Vgs For 3d-crmmentioning

confidence: 99%

Experimental Investigation of Vortex Generator Effect on Two- and Three-Dimensional NASA Common Research Models

Koike

Nakakita

Nakajima

et al. 2015

53rd AIAA Aerospace Sciences Meeting

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“…VGs energize the boundary layer by enhancing mixing between the higher momentum external flow and the low momentum near-wall flow. However, there is an obvious disadvantage in using VGs because they cause a parasitic drag component [6]. More recent work has found that subboundary layer vortex generators (SBVGs), see Fig.…”

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confidence: 99%

Effect of Microvortex Generators On Seperated Normal Shock/ Boundary Layer Interactions

Holden

Babinsky

2007

Journal of Aircraft

122

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Experiments have been performed in a blowdown supersonic wind tunnel to investigate the effect of subboundary layer vortex generators placed upstream of a normal shock/turbulent boundary layer interaction at a Mach number of 1.5 and a freestream Reynolds number of 28 10 6 . The Reynolds number based on the inflow boundary layer displacement thickness was 26,000. Two types of subboundary layer vortex generators were investigated: wedgeshaped and counter-rotating vanes. It was found that the vane-type subboundary layer vortex generators eliminated and the wedge-type subboundary layer vortex generators greatly reduced the shock-induced separation. When placed in the supersonic part of the flow, both types of subboundary layer vortex generators caused a wave pattern consisting of a shock, reexpansion, and shock. The reexpansion and double shocks are undesirable features because they equate to increased total pressure losses. Furthermore there are indications that the vortex intensity is reduced by the normal shock/boundary layer interaction. Overall, the vane-type subboundary layer vortex generators were the more effective devices as they eliminated the shock-induced separation and had the least detrimental effect on the shock structure. Nomenclaturefreestream flow velocity, ms 1 u = local flow velocity, ms 1 X = streamwise coordinate, mm Y = vertical coordinate, mm Z = spanwise coordinate, mm = boundary layer thickness, mm = boundary layer displacement thickness, mm R 0 1 u= e U e dy = boundary layer momentum thickness, mm R 0 u= e U e 1 u= e U e dy Subscripts 0 = total conditions 1 = upstream of shock 1 = freestream

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“…The effect of VGs was investigated by changing VG installation parameters, such as D v , H v , and β v . As the first step toward understanding the basic physics of corotating blade-type (rectangular) VGs described in the literature [1,5], infinite-span twodimensional (2-D) wings were evaluated by CFD [2] and corresponding wind-tunnel tests were conducted in the JAXA 0.8 × 0.45 m transonic wind tunnel using rectangular wings with a NASA SC(2)-0518 airfoil section [6] and a representative wing section of the NASA Common Research Model (CRM) [7,8]. As the second step, the three-dimensional (3-D) NASA CRM was used.…”

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confidence: 99%

Effect of Vortex Generators on Transonic Swept Wings

Ito¹,

Yamamoto²,

Kusunose³

et al. 2016

Journal of Aircraft

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This paper examines the effects of corotating blade-type vortex generators on transonic sweptback wings using computational fluid dynamics studies. Infinite-span (two-dimensional) swept wings are first considered to understand the basic physics of vortex generators. Sweep angles are given virtually to the wings by changing the freestream direction. Vortex generators are placed on the wings, and the visualized interactions of their tip vortices with the boundary layer reveal the relationship between the effect of the vortex generators and the wing sweep angle. The physics of vortex-generator tip vortices are then described to explain how vortex generators on swept wings efficiently suppress shock-induced separation by mixing boundary layers. It is also shown that the vortex-generator angle of incidence to the local flow can slightly improve the effect of the vortex generators but that wing sweep angle has a greater influence on their effect. Based on the discussion of infinite-span wings, the computational results of the NASA Common Research Model with and without vortex generators are finally examined and compared with the experiment. It is confirmed that toe-out vortex generators on the three-dimensional Common Research Model are as efficient as those on an infinite-span wing with a moderate sweep angle.

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Vortex Generator Installation Drag on an Airplane Near Its Cruise Condition

Cited by 14 publications

References 5 publications

Experimental Investigation of Vortex Generator Effect on Two- and Three-Dimensional NASA Common Research Models

Experimental Investigation of Vortex Generator Effect on Two- and Three-Dimensional NASA Common Research Models

Effect of Microvortex Generators On Seperated Normal Shock/ Boundary Layer Interactions

Effect of Vortex Generators on Transonic Swept Wings

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