Three-dimensional flow structure and aerodynamic loading on a revolving wing

Garmann, Daniel J.; Visbal, Miguel R.; Orkwis, Paul D.

doi:10.1063/1.4794753

Cited by 107 publications

(72 citation statements)

References 35 publications

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“…This configuration is similar to that reported in Garmann et al 22 except that they considered a 4% thickness wing and initiated the rotation using Eldredge's function (whereas we apply an impulsive start, i.e. step function).…”

Section: Ivb2 Revolving Wingsupporting

confidence: 59%

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Immersed Boundary Lattice Green Function methods for External Aerodynamics

Mengaldo

Liska

et al. 2017

23rd AIAA Computational Fluid Dynamics Conference

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In this paper, we document the capabilities of a novel numerical approach -the immersed boundary lattice Green's function (IBLGF)1 method -to simulate external incompressible flows over complex geometries. This new approach is built upon the immersed boundary method and lattice Green's functions to solve the incompressible Navier-Stokes equations. We show that the combination of these two concepts allows the construction of an efficient and robust numerical framework for the direct numerical and large-eddy simulation of external aerodynamic problems at moderate to high-Reynolds numbers.

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Section: Ivb2 Revolving Wingsupporting

confidence: 59%

“…step function). Figure 10 compares results obtained using the IBLGF method with those obtained by Garmann et al 22 Good agreement is observed between both approaches with some discrepancies that may partly arise from wing thickness and acceleration profile. Note that values in Garmann et al…”

Section: Ivb2 Revolving Wingsupporting

confidence: 53%

Immersed Boundary Lattice Green Function methods for External Aerodynamics

Mengaldo

Liska

et al. 2017

23rd AIAA Computational Fluid Dynamics Conference

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“…A stable LEV grows in the direction in which the vorticity is extracted. The vorticity and circulation of the LEV can significantly increase the lift and thus it is exploited on both man-made and natural flyers [3,4,5,6]. Remarkably, it has been identified across a wide range of Re.…”

Section: The Leading Edge Vortexmentioning

confidence: 99%

The leading-edge vortex of yacht sails

Arredondo-Galeana

Viola

2018

Ocean Engineering

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It has been suggested that a stable Leading Edge Vortex (LEV) can be formed from the sharp leading edge of asymmetric spinnakers. If the LEV remains stably attached to the leading edge, it provides an increase in the thrust force. Until now, however, the existence of a stable and attached LEV has only been shown by numerical simulations. In the present work we experimentally verify, for the first time, that a stable LEV can be formed on an asymmetric spinnaker. We tested a 3D printed rigid sail in a water flume at a chord-based Reynolds number of ca. 104 . The sail was tested in isolation (no hull and rigging) at an incidence with the flow equivalent to an apparent wind angle of 55• and a heel angle of 10 • . The flow field was measured with particle image velocimetry over horizontal cross sections. We found that on the leeward side of the sail, the flow separates at the leading edge reattaching further downstream and forming a stable LEV. The LEV grows in diameter from the root to the tip of the sail, where it merges with the tip vortex. We detected the LEV using the γ 1 and γ 2 criteria, and we verified its stability over time. The lift contribution provided by the LEV was computed solving a complex potential model of each sail section. This analysis showed that the LEV provides more than 10% of the total sail's lift. These findings suggests that the performance of asymmetric spinnakers could be significantly enhanced by promoting a stable LEV.

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“…Though bird flight and landing is a three-dimensional problem, two-dimensional flow topologies often dominate in highly unsteady manoeuvres, as was shown by Garmann et al (2013), and so we restrict ourselves to the two-dimensional pitch-up problem.…”

Section: Introductionmentioning

confidence: 99%

Unsteady dynamics of rapid perching manoeuvres

2015

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A perching bird is able to rapidly decelerate while maintaining lift and control, but the underlying aerodynamic mechanism is poorly understood. In this work we perform a study on a simultaneously decelerating and pitching aerofoil section to increase our understanding of the unsteady aerodynamics of perching. We first explore the problem analytically, developing expressions for the added-mass and circulatory forces arising from boundary-layer separation on a flat-plate aerofoil. Next, we study the model problem through a detailed series of experiments at Re = 22000 and two-dimensional simulations at Re = 2000. Simulated vorticity fields agree with particle image velocimetry measurements, showing the same wake features and vorticity magnitudes. Peak lift and drag forces during rapid perching are measured to be more than 10 times the quasi-steady values. The majority of these forces can be attributed to added-mass energy transfer between the fluid and aerofoil, and to energy lost to the fluid by flow separation at the leading and trailing edges. Thus, despite the large angles of attack and decreasing flow velocity, this simple pitch-up manoeuvre provides a means through which a perching bird can maintain high lift and drag simultaneously while slowing to a controlled stop.

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Three-dimensional flow structure and aerodynamic loading on a revolving wing

Cited by 107 publications

References 35 publications

Immersed Boundary Lattice Green Function methods for External Aerodynamics

Immersed Boundary Lattice Green Function methods for External Aerodynamics

The leading-edge vortex of yacht sails

Unsteady dynamics of rapid perching manoeuvres

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