Influence of the pivot location on the thrust and propulsive efficiency performance of a two-dimensional flapping elliptic airfoil in a forward flight

A mechanism of hovering flight of small insects which is called the Weis-Fogh mechanism is applied to ship propulsion. A model of the propulsion mechanism is proposed, which is based on a two-dimensional model of the Weis-Fogh mechanism and consists of one or two wings in a square channel. The dynamic properties of the model are studied experimentally, and the propulsive efficiency obtained is as high as 75 percent. A model ship equipped with this propulsion mechanism was made, and working tests performed. The model ship sailed very smoothly and the moving speed of the wings was small compared with the advancing speed of the ship.

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A Two-Dimensional Theory for Rotor Blade Flutter in Forward Flight

Journal of Aircraft ◽

10.2514/3.59198 ◽

1971 ◽

Vol 8 (12) ◽

pp. 1008-1015 ◽

Cited By ~ 5

Author(s):

K. W. SHIPMAN ◽

E. R. WOOD

Keyword(s):

Rotor Blade ◽

Two Dimensional ◽

Dimensional Theory ◽

Forward Flight ◽

Blade Flutter

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A study of wake structures of a heaving two-dimensional elliptic airfoil using DPIV technique

45th AIAA Aerospace Sciences Meeting and Exhibit ◽

10.2514/6.2007-276 ◽

2007 ◽

Author(s):

K. B. Lua ◽

T. T. Lim ◽

K. S. Yeo ◽

G. Y. Oo

Keyword(s):

Two Dimensional ◽

Elliptic Airfoil

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Parametric study of a corrugated airfoil in a forward flight at ultra-low Reynolds number

SN Applied Sciences ◽

10.1007/s42452-020-04105-y ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

Mahmoud E. Abd El-Latief ◽

Khairy Elsayed ◽

Mohamed M. Abdelrahman

Keyword(s):

Reynolds Number ◽

Phase Difference ◽

Lift Force ◽

Thrust Force ◽

Angle Of Attack ◽

Initial Angle ◽

Aerodynamic Forces ◽

Forward Flight ◽

Propulsive Efficiency ◽

Stroke Amplitude

AbstractIn the current study, the mid cross section of the dragonfly forewing was simulated at ultra-low Reynolds number. The study aims to understand better the contribution of corrugations found along the wing on the aerodynamic performance during a forward flight. Different flapping parameters were employed. FLUENT solver was used to solve unsteady, two-dimensional, laminar, incompressible Navier–Stokes equations. The results revealed that any stroke amplitude less than 1cm generated no thrust force. The stroke amplitude had to be increased to form the reversed Kármán vortices responsible for generating thrust force. The highest propulsive efficiency was found in the Strouhal number range 0.2 < St < 0.4 with a peak efficiency of 57% at St = 0.39. Changing the phase difference between pitching and plunging motions from advanced to synchronized caused lift force to drop 91% and thrust force to increase by 15%. On the other hand, changing the phase difference from synchronized to delayed caused lift and thrust forces to increase by 89% and 36%, respectively, and propulsive efficiency to deteriorate significantly. In all performed simulations, the airfoil was assumed to start motion from rest with no initial angle of attack. The increase in initial angle of attack generates a very high lift force with a fair loss for both thrust force and propulsive efficiency. The decomposition of flapping motion into its elementary motions revealed that the aerodynamic forces generated are a non-linear superposition from both pure pitching and pure plunging aerodynamic forces. This can be attributed to the non-linear interaction between unsteady vortices generated from these decomposed motions.

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Swimming of a waving plate

Journal of Fluid Mechanics ◽

10.1017/s0022112061000949 ◽

1961 ◽

Vol 10 (3) ◽

pp. 321-344 ◽

Cited By ~ 277

Author(s):

T. Yao-Tsu Wu

Keyword(s):

General Theory ◽

Phase Velocity ◽

Wave Train ◽

Leading Edge ◽

Basic Mechanism ◽

Simplified Model ◽

Two Dimensional ◽

Propulsive Efficiency ◽

Fish Propulsion ◽

Solid Plate

The purpose of this paper is to study the basic principle of fish propulsion. As a simplified model, the two-dimensional potential flow over a waving plate of finite chord is treated. The solid plate, assumed to be flexible and thin, is capable of performing the motion which consists of a progressing wave of given wavelength and phase velocity along the chord, the envelope of the wave train being an arbitrary function of the distance from the leading edge. The problem is solved by applying the general theory for oscillating deformable airfoils. The thrust, power required, and the energy imparted to the wake are calculated, and the propulsive efficiency is also evaluated. As a numerical example, the waving motion with linearly varying amplitude is carried out in detail. Finally, the basic mechanism of swimming is elucidated by applying the principle of action and reaction.

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