Numerical computation of flapping-wing propulsion and power extraction

Jones, Kevin D.; Platzer, Max F.

doi:10.2514/6.1997-826

Cited by 138 publications

(90 citation statements)

References 19 publications

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“…This was studied in some detail in Ref. 23, where it was shown that the propulsive performance of a apping foil was signi cantly enhanced near a ground plane. This opposing-plunge or ground-e ect con guration o ers the additional benets of mechanical and aerodynamic balanced loading in the vertical direction, and is therefore desirable for our wind-tunnel model.…”

Section: Con Gurationsmentioning

confidence: 99%

“…Jones et al 7 compared wake structures behind apping wings experimentally photographed and numerically predicted, and demonstrated that the formation and evolution of these unsteady wakes is essentially an inviscid phenomenon over a broad range of Strouhal numbers. Jones and Platzer 23 performed extensive n umerical apping-wing propulsion calculations using panel methods, and found a large performance enhancement for an airfoil apping in ground e ect, an e ect often utilized by birds.…”

Section: Introductionmentioning

confidence: 99%

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An experimental and numerical investigation of flapping-wing propulsion

Platzer

Jones

1999

37th Aerospace Sciences Meeting and Exhibit

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Flapping-wing propulsion is investigated experimentally and numerically with direct comparisons between experimental and numerical thrust measurements for several geometrically simple con gurations. Numerical simulations are performed using linear theory, and a previously developed, unsteady panel method that models one or two independently moving airfoils with three-degrees of freedom and non-linear deforming wakes. Experiments are carried out in the Naval Postgraduate School 5 0 5 0 low-speed tunnel. A apping mechanism that approximates the two-dimensional motions modeled by the panel code is suspended with cables in the wind tunnel, and thrust measurements are made by measuring the streamwise displacement of the model using a laser range-nder. The experimental apping mechanism utilizes variable aspectratio wings and optional tip plates to investigate the e ect of three-dimensionality. The device aps two airfoils, each with two degrees of freedom and adjustable pitch and plunge amplitudes, and additional stationary wings may be attached up and/or downstream of the apping wings to investigate interference e ects. Nomenclature b = wing span c = c hord length C d = drag coe cient per unit span, D=(q 1 c) C l = lift coe cient per unit span, L=(q 1 c) C m = moment coe cient per unit span, M=(q 1 c 2 )

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Section: Con Gurationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An experimental and numerical investigation of flapping-wing propulsion

Platzer

Jones

1999

37th Aerospace Sciences Meeting and Exhibit

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“…Numerous authors have studied the problem of a 2D airfoil in pure heaving motion, in which the airfoil oscillates vertically with a zero angle of attack [Jones and Platzer, 1997, Wang, 2000, Lewin and Haj-Hariri, 2003, Lua et al, 2007, Wei and Zheng, 2014, Choi et al, 2015. This simplified configuration is still a rich model where some of the main features of flapping flight are present, for example, the leading and trailing edge vortices.…”

Section: Introductionmentioning

confidence: 99%

On the aerodynamic forces on heaving and pitching airfoils at low Reynolds number

2017

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The influence that the kinematics of pitching and heaving 2D airfoils have on the aerodynamic forces is investigated using Direct Numerical Simulations and a force decomposition algorithm. Large amplitude motions are considered (of the order of one chord), with moderate Reynolds numbers and reduced frequencies of order O(1), varying the mean pitch angle and the phase shift between the pitching and heaving motions. Our results show that the surface vorticity contribution (viscous effects) to the aerodynamic force is negligible compared to the contributions from the body motion (fluid inertia) and the vorticity within the flow (circulation). For the range of parameters considered here, the latter tends to be instantaneously oriented in the direction normal to the chord of the airfoil. Based on the results discussed in the paper, a reduced order model for the instantaneous aerodynamic force is proposed, taking advantage of the force decomposition and the chord-normal orientation of the contribution from vorticity within the flow to the total aerodynamic force. The predictions of the proposed model are compared to those of a similar model from the literature, showing a noticeable improvement on the prediction of the mean thrust, and a smaller improvement on the prediction of mean lift and the instantaneous force coefficients.

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“…Obviously, the two scenarios can be considered as the cases with opposite phase lags between the pitching and plunging motions. It should be noted that, as reported in Jones and Platzer (1997) and Schouveiler et al (2005), a better propulsive performance can be achieved when a suitable phase lag was adopted for an airfoil in combined pitching and plunging motion. It is well known that the generation of wake vortices near the airfoil trailing edge is due to the pressure differences between the upper and lower sides of the pitching airfoil.…”

Section: Discussionmentioning

confidence: 97%

An experimental study of the effects of pitch-pivot-point location on the propulsion performance of a pitching airfoil

Tian

Bodling

Liu

et al. 2016

Journal of Fluids and Structures

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a b s t r a c tAn experimental investigation was conducted to characterize the evolution of the unsteady vortex structures in the wake of a pitching airfoil with the pitch-pivot-point moving from 0.16C to 0.52C (C is the chord length of the airfoil). The experimental study was conducted in a low-speed wind tunnel with a symmetric NACA0012 airfoil model in pitching motion under different pitching kinematics (i.e., reduced frequency k ¼3.8-13.2). A high-resolution particle image velocimetry (PIV) system was used to conduct detailed flow field measurements to quantify the characteristics of the wake flow and the resultant propulsion performance of the pitching airfoil. Besides conducting "free-run" PIV measurements to determine the ensemble-averaged velocity distributions in the wake flow, "phase-locked" PIV measurements were also performed to elucidate further details about the behavior of the unsteady vortex structures. Both the vorticity-moment theorem and the integral momentum theorem were used to evaluate the effects

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Numerical computation of flapping-wing propulsion and power extraction

Cited by 138 publications

References 19 publications

An experimental and numerical investigation of flapping-wing propulsion

An experimental and numerical investigation of flapping-wing propulsion

On the aerodynamic forces on heaving and pitching airfoils at low Reynolds number

An experimental study of the effects of pitch-pivot-point location on the propulsion performance of a pitching airfoil

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