Aerodynamics and Vortex Flowfield of a Slender Delta Wing With Apex Flap and Tip Flap

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
T. Lee ◽  
L. S. Ko
Keyword(s):  
Vortex Flow ◽  
Opposite Effect ◽  
Particle Image ◽  
Delta Wing ◽  
Leading Edge ◽  
Piv Measurements ◽  
Injection Flow ◽  
Image Velocimetry ◽  
Edge Vortex ◽  
Flap Deflection

The effect of apex flap and tip flap, deflected both independently and jointly, on the vortex flow and lift generation of a 65 deg-sweep delta wing was investigated experimentally. The drooped apex flap produced a higher lift at medium-to-high angle of attack regime and also a delayed stall. The anhedral (introduced by the downward tip flap) generally promoted lift increment, whereas dihedral had the opposite effect. Meanwhile, the joint apex and tip flap deflection gave a delayed leading-edge vortex (LEV) breakdown and an enhanced lift. The LEVs were generally drawn closer to the wing upper surface, while being pushed further away from the wing centerline by the application of apex flap and tip flap. The flap also modified the vorticity distribution in the LEV; the bursting behavior was, however, not affected. Dye-injection flow visualization and particle image velocimetry (PIV) measurements of the vortex flow were also discussed.

Vortex flow and lift generation of a non-slender reverse delta wing

2016 ◽  
Vol 231 (13) ◽  
pp. 2438-2451
Author(s):  
T Lee ◽  
LS Ko
Keyword(s):  
Particle Image Velocimetry ◽  
Lift Force ◽  
Vortex Flow ◽  
Particle Image ◽  
Delta Wing ◽  
Lower Surface ◽  
Force Balance ◽  
Flow Parameters ◽  
Image Velocimetry ◽  
Spanwise Vortex

The vortex flow and lift force generated by a 50°-sweep non-slender reverse delta wing were investigated via particle image velocimetry, together with flow visualization and force balance measurement, at Re = 11,000. The non-slender reverse delta wing produced a delayed stall but a lower lift compared to its delta wing counterpart. The stalling mechanism was also found to be triggered by the disruption of the multiple spanwise vortex filaments developed over the upper wing surface. The vortex flowfield was, however, characterized by the co-existence of reverse delta wing vortices and multiple shear-layer vortices. The outboard location of the reverse delta wing vortex further implies that the lift force is mainly generated by the wing lower surface while the upper surface acts as a wake generator. The spatial progression of the flow parameters of the vortex generated by the non-slender reverse delta wing as a function of α was also discussed.

Wake Behavior Around Flapping Wings of Model Hawkmoth Moving Sideways

2019 ◽  
Author(s):  
Jong-Seob Han ◽  
Jae-Hung Han
Keyword(s):  
Particle Image ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Digital Particle Image Velocimetry ◽  
Flapping Wings ◽  
Windward Side ◽  
Leeward Side ◽  
Image Velocimetry ◽  
Wake Interaction ◽  
Edge Vortex

Abstract This study investigated nearwake behaviors around flapping wings moving sideways. A dynamically scaled-up flapping manipulator was installed on a servo-driven towing carriage to give the sideways movement. In the single wing configuration, the wing in the windward side did not encounter any noticeable effects on the aerodynamic characteristics. The wing in the leeward side, on the other hand, experienced a substantial lift augmentation. We found a stretched leading-edge vortex (LEV) on the wing in the leeward side, implying the additional feeding flux into the LEV. In this case, the moving sideways gave a continuous lateral wind, which became the source to maintain the lift augmentation with the less downward component. We also found that the moving sideways rather intensified the interaction between the wake of the wing in the windward side and the contralateral wing, i.e., the wing-wake interaction. Accordingly, the lift augmentation on the wing in the leeward side practically disappeared by the wing-wake interaction. A digital particle image velocimetry for nearwake behaviors found the less developed trailing-edge shear layer and wingroot vortex traces. This implied that the massive downwash induced by the wing in the windward side was the main source to neutralize the lift augmentation on the contralateral wing.

scholarly journals The Leading-Edge Vortex of Swift Wings

2017 ◽  
Author(s):  
Rowan Eveline Muir ◽  
Ignazio Maria Viola
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Leading Edge ◽  
Leading Edge Vortex ◽  
Wing Model ◽  
Image Velocimetry ◽  
Edge Vortex ◽  
First Time ◽  
Swept Wings ◽  
Sharp Leading Edge

1AbstractRecent 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 will serve to add understanding to the complex aerodynamics of natural fliers. In this investigation, the wing of a common swift Apus apus is simplified to a model with swept wings and a sharp leading-edge, making it readily comparable to a model delta shaped wing of the same leading-edge geometry. Particle image velocimetry provides an understanding of the effect of the tapering swift wing on LEV development and stability, compared with the delta wing model. For the first time a dual LEV is recorded on a swift shaped wing, where it is found across all tested conditions. It is shown that the span-wise location of LEV breakdown is governed by the local chord rather than Reynolds number or angle of attack. These findings suggest that the common swift is able to generate a dual LEV while gliding, potentially delaying vortex breakdown by exploiting other features non explored here, such as wing twist and flexibility. It is further suggested that the vortex system could be used to damp loading fluctuations, reducing energy expenditure, rather than for lift augmentation.

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.

scholarly journals Leading-edge vortices over swept-back wings with varying sweep geometries

2019 ◽  
Vol 6 (7) ◽  
pp. 190514 ◽  
Author(s):  
William B. Lambert ◽  
Mathew J. Stanek ◽  
Roi Gurka ◽  
Erin E. Hackett
Keyword(s):  
Particle Image ◽  
Delta Wing ◽  
Leading Edge ◽  
Micro Air Vehicles ◽  
Linear Sweep ◽  
Image Velocimetry ◽  
Gliding Flight ◽  
Swirling Strength ◽  
The Common ◽  
Leading Edge Vortices

Micro air vehicles are used in a myriad of applications, such as transportation and surveying. Their performance can be improved through the study of wing designs and lift generation techniques including leading-edge vortices (LEVs). Observation of natural fliers, e.g. birds and bats, has shown that LEVs are a major contributor to lift during flapping flight, and the common swift ( Apus apus ) has been observed to generate LEVs during gliding flight. We hypothesize that nonlinear swept-back wings generate a vortex in the leading-edge region, which can augment the lift in a similar manner to linear swept-back wings (i.e. delta wing) during gliding flight. Particle image velocimetry experiments were performed in a water flume to compare flow over two wing geometries: one with a nonlinear sweep (swift-like wing) and one with a linear sweep (delta wing). Experiments were performed at three spanwise planes and three angles of attack at a chord-based Reynolds number of 26 000. Streamlines, vorticity, swirling strength, and Q -criterion were used to identify LEVs. The results show similar LEV characteristics for delta and swift-like wing geometries. These similarities suggest that sweep geometries other than a linear sweep (i.e. delta wing) are capable of creating LEVs during gliding flight.

Control of Leading Edge Vortices Using Apex Flap over Non-Slender Delta Wing

2013 ◽  
Vol 390 ◽  
pp. 12-17
Author(s):  
Hafiz Laiq-Ur Rehman
Keyword(s):  
Vortex Flow ◽  
Vortex Breakdown ◽  
Delta Wing ◽  
Leading Edge ◽  
Pressure Probe ◽  
Sweep Angle ◽  
Strong Shear ◽  
Flap Deflection ◽  
Probe Measurements ◽  
Leading Edge Vortices

This manuscript presents the vortex flow structure over non-slender delta wing with leading edge sweep angle, Λ=45°. A comprehensive investigation has been conducted in wind tunnel at Reynolds number ranging from, Re = 247,000 - 445,000. Seven-hole pressure probe measurements for axial vorticity, axial velocity, vortex trajectory and pressure variations are presented at various chordwise stations and angles of incidences. It was demonstrated that weak leading edge vortices are generated very close to the wing surface with strong shear layer which move upward and outboard with apex flap deflection. Reattachment line move towards wing root chord with the increase in angle of attack. Passive apex flap has been used to control the leading edge vortices and to delay the vortex breakdown. It is recognized that vortex breakdown was delayed by 8% by downward apex flap deflection.

Vortex Flow Hypothesis for Rotor Blades in Reverse Flow

2013 ◽  
Author(s):  
Michael Mayo ◽  
Nicholas Motahari ◽  
Vrishank Raghav ◽  
Narayanan Komerath
Keyword(s):  
Vortex Flow ◽  
Delta Wing ◽  
Reverse Flow ◽  
Leading Edge ◽  
Flow Region ◽  
Rotor Blades ◽  
Bending Moments ◽  
High Speeds ◽  
Edge Vortex ◽  
Pressure Perturbations

Slowed rotors are used to increase the cruise efficiency and maneuverability of rotorcraft at high speeds. Operation at high rotor advance ratios implies that the blades encounter reverse flow on the retreating side of the rotor disc. The resulting increased pitch link loads and bending moments could shorten component life. Previous studies have shown significant rotor blade pressure perturbations in the reverse flow region, which are not fully accounted for using current prediction methodologies. The hypothesis explored here is that the blade trailing edge in reverse flow produces a vortex similar to the leading edge vortex on a sharp-edged delta wing. The Polhamus model for delta wing lift is modified for use on yawed rotor blades. Lift, drag and pitching moment data acquired on a static yawed blade in reverse flow supports analytical results. Surface tuft flow visualization confirms the existence of an attached, span-wise vortex.

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