Planform and Camber Effects on the Aerodynamics of Low-Reynolds-Number Wings

Swanson, Taylor A.; Isaac, Kakkattukuzhy M.

doi:10.2514/1.45921

Cited by 14 publications

(6 citation statements)

References 26 publications

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“…2 [8] indicates the parameters in the camber line design. Based on previous studies [5][6][7][8], a positive camber of 5.8%…”

Section: A Geometry Descriptionmentioning

confidence: 89%

“…However, there were no particular reasons provided to explain this phenomenon. Swanson and Isaac [5] studied planform and camber effects on low-Reynolds-number aerodynamics computationally. An extremely low Reynolds number of 500 was investigated, and they showed that the tip vortex is the dominant flow, and it forms the highly three-dimensional (3-D) low-velocity region at high incidences.…”

mentioning

confidence: 99%

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Planform Effects for Low-Reynolds-Number Thin Wings with Positive and Reflex Cambers

Chen

Qin

2013

Journal of Aircraft

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To understand the planform effects on low-Reynolds-number aerodynamic characteristics for micro air vehicles, various cambered thin plate wings were studied by numerical simulations based on Reynolds-averaged Navier-Stokes solutions with transition modeling. Six wing planforms, with the same wing aspect ratio and area, a positive camber at the quarter chord location, and a reflex camber near the trailing edge for longitudinal stability were selected for the study. They include a rectangular wing, four taped wings with the same taper ratio but different leading-edge sweeps, a Zimmerman wing, and an inverse-Zimmerman wing. For validation with available windtunnel experimental data, an investigation of a circular wing planform with a similarly cambered profile is also presented. The results show that the Zimmerman wing planform gives the best lift-to-drag ratio at the design condition, whereas the tapered wing with higher leading-edge sweep produces higher maximum lift. Flow separation and vortical flow structures on the upper wing surface are presented to gain insight into the different aerodynamic characteristics for the different planforms.

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“…2 [8] indicates the parameters in the camber line design. Based on previous studies [5][6][7][8], a positive camber of 5.8%…”

Section: A Geometry Descriptionmentioning

confidence: 89%

mentioning

confidence: 99%

Planform Effects for Low-Reynolds-Number Thin Wings with Positive and Reflex Cambers

Chen

Qin

2013

Journal of Aircraft

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“…As the incidence increases, flow separation, transition, and reattachment appear, which affect strongly the flow structure, and hence the lifting surface performance. Lian and Shyy [2] and Swanson and Isaac [3] indicated that transition can occur for Re c ≥ 10 4 , and therefore a transition model is required in this flow condition.…”

Section: Introductionmentioning

confidence: 97%

Three-Dimensional Laminar-Separation Bubble on a Cambered Thin Wing at Low Reynolds Numbers

Chen

Qin

Nowakowski

2013

Journal of Aircraft

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Three-dimensional laminar-separation bubbles on a cambered thin wing with an aspect ratio of 6 at a Reynolds number of 60,000 have been investigated by solving the Reynolds-averaged Navier-Stokes equations. The k-ω shearstress transport γ-Re θ turbulence-transition model is used to account for the effect of transition on the laminar separation-bubble development. The aerodynamic forces are compared with the experimental data available for validation. The laminar-separation bubble is shown to evolve in its shape and dimension in both chord and span directions with increasing incidence due to its interaction with the wing-tip flow and the trailing-edge separation. The strongest three-dimensional effects are found at a moderate incidence of 6 deg and at higher incidences beyond 10 deg. Within the incidence range, the two-dimensional airfoil results are not reproduced at any of the span locations, including the symmetry plane, in the three-dimensional wing case. Generally, the chordwise development of the threedimensional laminar-separation-bubble at the symmetry plane is delayed as compared with the two-dimensional laminar-separation bubble. Another noticeable point is the association of a sudden increase in lift-curve slope due to abrupt expansion of the laminar-separation bubble at a certain incidence. This phenomenon is observed in both the two-and three-dimensional cases, but at different incidences. Nomenclature= three-dimensional and two-dimensional drag, respectively, N L, l = three-dimensional and two-dimensional lift, respectively, N L bc ∕c = laminar-separation-bubble length in chordwise direction L bz ∕z = laminar-separation-bubble length in spanwise direction Re c = Reynolds number based on chord S = wing area, m 2 T i = turbulence-intensity level t = thickness, m u ∞ = incoming flow velocity, m∕s X R ∕c = reattachment point X S ∕c = separation point X Tr ∕c = transition point y = distance in wall coordinates z∕c = spanwise location α = incidence/angle of attack, deg γ = intermittency Δu = velocity changes over the length of the bubble Δx = bubble length θ s = momentum thickness at separation μ = molecular viscosity μ t = eddy viscosity v = kinematic viscosity ρ = density τ = wall shear stress ω = specific turbulence dissipation rate

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“…Kim et al [17] conducted threedimensional unsteady simulation of a blowfly's forward flight, and unveiled the role of three-dimensional vortical structure in unsteady aerodynamic force generation. Swanson and Isaac [18] investigated planform and camber effects on unsteady aerodynamics of three-dimensional wing in constant freestream at various angles of attack and low Reynolds number. Four types of wings were simulated to identify dominant flow features around each wing.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional Unsteady Aerodynamic Characteristics of Wing-body-vortex Interactions in Insects' Flapping Flight

Lee

Kim

2013

31st AIAA Applied Aerodynamics Conference

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This paper investigates the unsteady aerodynamic features of wing-body-vortex interactions and the effects of geometric factors such as wing shape and body angle in insects' flapping motions under forward flight condition. A realistic wing trajectory, called the 'figure-of-eight' motion, is extracted from a blowfly (Phormia regina)'s tethered flight experiment under the freestream velocity of 2.75m/s. Since the flow field around the blowfly exhibits the characteristics of low-Reynolds number flow, three-dimensional unsteady incompressible Navier-Stokes equations are employed as the governing equations. In order to simulate the realistic insect flapping flight including geometric and kinematical complexity with a sufficient level of grid quality, the overset grid technique is used. From the authors' previous researches on two-and three-dimensional rigid wing simulation, it has been observed that the pattern of vortical flows and the interaction of vortices play an significant role in generating unsteady aerodynamic forces and determining the propulsive efficiency of flapping motion. Detailed numerical simulations of five types of wings are carried out under various body angles to examine unsteady flow characteristics resulting from the wing-body-vortex interactions, and the results are compared with those of the wing only case. Nomenclature c m = mean chord length U ∞ = freestream velocity U max = maximum wing velocity at aerodynamic mean chord ν = freestream kinematic viscosity Re = Reynolds number (=U max c m /ν)= flapping frequency in Hertz k = reduced frequency in terms of c m (= fc m /U max ) t = non-dimensional time T = non-dimensional flapping period χ = body angle α(t) = pitch angle motion ф(t) = position angle motion θ(t) = elevation angle motion

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Planform and Camber Effects on the Aerodynamics of Low-Reynolds-Number Wings

Cited by 14 publications

References 26 publications

Planform Effects for Low-Reynolds-Number Thin Wings with Positive and Reflex Cambers

Planform Effects for Low-Reynolds-Number Thin Wings with Positive and Reflex Cambers

Three-Dimensional Laminar-Separation Bubble on a Cambered Thin Wing at Low Reynolds Numbers

Three-dimensional Unsteady Aerodynamic Characteristics of Wing-body-vortex Interactions in Insects' Flapping Flight

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