Effect of leading-edge vortex flaps on aerodynamic performance of delta wings

1981 ◽  
Vol 18 (9) ◽  
pp. 796-798 ◽  
Author(s):  
C. Subba Reddy
Keyword(s):  
Leading Edge ◽  
Aerodynamic Performance ◽  
Delta Wings ◽  
Leading Edge Vortex ◽  
Edge Vortex

scholarly journals Rotor performance enhancement through blade surging

2019 ◽  
Vol 11 ◽  
pp. 175682931984427
Author(s):  
T Bensebaa ◽  
T Jardin ◽  
S Prothin ◽  
N Doue
Keyword(s):  
Large Scale ◽  
Performance Enhancement ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Short Paper ◽  
Optimal Frequency ◽  
Leading Edge Vortex ◽  
Disk Plane ◽  
Edge Vortex ◽  
Rotor Disk

This short paper introduces a new concept of rotor where the blades undergo a periodic surging motion in the rotor disk plane. It is shown that the unsteady actuation induces aerodynamic phenomenon that can enhance both rotor thrust and efficiency, depending on the amplitude and frequency of actuation. In particular, the increase in aerodynamic performance is found to correlate with the development of a large scale leading edge vortex. Accordingly, the optimal frequency is found to correlate with the formation time of this vortex.

scholarly journals Evolution of the leading-edge vortex over a flapping wing mechanism

2020 ◽  
Vol 14 (2) ◽  
pp. 6888-6894
Author(s):  
Muhamad Ridzuan Arifin ◽  
A.F.M. Yamin ◽  
A.S. Abdullah ◽  
M.F. Zakaryia ◽  
S. Shuib ◽  
...  
Keyword(s):  
Aerodynamic Force ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Flapping Wing ◽  
Unsteady State ◽  
Leading Edge Vortex ◽  
Edge Vortex ◽  
Advance Ratio ◽  
Lift Enhancement ◽  
Lift And Drag

Leading-edge vortex governs the aerodynamic force production of flapping wing flyers. The primary factor for lift enhancement is the leading-edge vortex (LEV) that allows for stall delay that is associated with unsteady fluid flow and thus generating extra lift during flapping flight. To access the effects of LEV to the aerodynamic performance of flapping wing, the three-dimensional numerical analysis of flow solver (FLUENT) are fully applied to simulate the flow pattern. The time-averaged aerodynamic performance (i.e., lift and drag) based on the effect of the advance ratio to the unsteadiness of the flapping wing will result in the flow regime of the flapping wing to be divided into two-state, unsteady state (J<1) and quasi-steady-state(J>1). To access the benefits of aerodynamic to the flapping wing, both set of parameters of velocities 2m/s to 8m/s at a high flapping frequency of 3 to 9 Hz corresponding to three angles of attacks of α = 0o to α = 30o. The result shows that as the advance ratio increases the generated lift and generated decreases until advance ratio, J =3 then the generated lift and drag does not change with increasing advance ratio. It is also found that the change of lift and drag with changing angle of attack changes with increasing advance ratio. At low advance ratio, the lift increase by 61% and the drag increase by 98% between α =100 and α =200. The lift increase by 28% and drag increase by 68% between α = 200 and α = 300. However, at high advance ratio, the lift increase by 59% and the drag increase by 80% between α =100 and α = 200, while between α =200 and α =300 the lift increase by 20% and drag increase by 64%. This suggest that the lift and drag slope decreases with increasing advance ratio. In this research, the results had shown that in the unsteady state flow, the LEV formation can be indicated during both strokes. The LEV is the main factor to the lift enhancement where it generated the lower suction of negative pressure. For unsteady state, the LEV was formed on the upper surface that increases the lift enhancement during downstroke while LEV was formed on the lower surface of the wing that generated the negative lift enhancement. The LEV seem to breakdown at the as the wing flap toward the ends on both strokes.      

Circulation criterion to predict leading-edge vortex breakdown over delta wings

1997 ◽  
Author(s):  
X. Huang ◽  
Y. Sun ◽  
E. Hanff ◽  
X. Huang ◽  
Y. Sun ◽  
...  
Keyword(s):  
Vortex Breakdown ◽  
Leading Edge ◽  
Delta Wings ◽  
Leading Edge Vortex ◽  
Edge Vortex

scholarly journals The leading-edge vortex of swift wing-shaped delta wings

2017 ◽  
Vol 4 (8) ◽  
pp. 170077 ◽  
Author(s):  
Rowan Eveline Muir ◽  
Abel Arredondo-Galeana ◽  
Ignazio Maria Viola
Keyword(s):  
Reynolds Number ◽  
Delta Wing ◽  
Leading Edge ◽  
Trailing Edge ◽  
Delta Wings ◽  
Leading Edge Vortex ◽  
Wing Model ◽  
Image Velocimetry ◽  
Edge Vortex ◽  
First Time

Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the leading-edge vortex (LEV) for lift generation in a variety of flight conditions. A well-documented example of an LEV is that generated by aircraft with highly swept, delta-shaped wings. While the wing aerodynamics of a manoeuvring aircraft, a bird gliding and a bird in flapping flight vary significantly, it is believed that this existing knowledge can serve to add understanding to the complex aerodynamics of natural fliers. In this investigation, a model non-slender delta-shaped wing with a sharp leading edge is tested at low Reynolds number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus . The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the unmodified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift wing-shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta-shaped wing.

On the roles of chord-wise flexibility in a flapping wing with hovering kinematics

2010 ◽  
Vol 659 ◽  
pp. 94-115 ◽  
Author(s):  
JEFF D. ELDREDGE ◽  
JONATHAN TOOMEY ◽  
ALBERT MEDINA
Keyword(s):  
Stokes Equations ◽  
Leading Edge ◽  
Relative Sensitivity ◽  
Aerodynamic Performance ◽  
Flexible Wings ◽  
Leading Edge Vortex ◽  
Flexible Wing ◽  
Wide Range ◽  
Edge Vortex ◽  
Rigid Wing

The aerodynamic performance of a flapping two-dimensional wing section with simplified chord-wise flexibility is studied computationally. Bending stiffness is modelled by a torsion spring connecting two or three rigid components. The leading portion of the wing is prescribed with kinematics that are characteristic of biological hovering, and the aft portion responds passively. Coupled simulations of the Navier–Stokes equations and the wing dynamics are conducted for a wide variety of spring stiffnesses and kinematic parameters. Performance is assessed by comparison of the mean lift, power consumption and lift per unit power, with those from an equivalent rigid wing, and two cases are explored in greater detail through force histories and vorticity snapshots. From the parametric survey, four notable mechanisms are identified through which flexible wings behave differently from rigid counterparts. Rigid wings consistently require more power than their flexible counterparts to generate the same kinematics, as passive deflection leads to smaller drag and torque penalties. Aerodynamic performance is degraded in very flexible wings undergoing large heaving excursions, caused by a premature detachment of the leading-edge vortex. However, a mildly flexible wing has consistently good performance over a wide range of phase differences between pitching and heaving – in contrast to the relative sensitivity of a rigid wing to this parameter – due to better accommodation of the shed leading-edge vortex into the wake during the return stroke, and less tendency to interact with previously shed trailing-edge vortices. Furthermore, a flexible wing permits lift generation even when the leading portion remains nearly vertical, as the wing passively deflects to create an effectively smaller angle of attack, similar to the passive pitching mechanism recently identified for rigid wings. It is found that an effective pitch angle can be defined that accounts for wing deflection to align the results with those of the equivalent rigid wing.

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