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Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods
Published on: April 23, 2018
Dual leading-edge vortices on flapping wings.
Yuan Lu1, Gong Xin Shen, Guo Jun Lai
1Full Flow Field Observation and Measurement, Institute of Fluid Mechanics, Beijing University of Aeronautics and Astronautics, Beijing 100083, People's Republic of China.
The Journal of Experimental Biology
|December 5, 2006
Summary
This study confirms dual leading-edge vortices (LEVs) on flapping wings, similar to delta wings. These dual LEVs form at high angles of attack and Reynolds numbers, with implications for understanding insect flight aerodynamics.
Area of Science:
- Fluid Dynamics
- Aerodynamics
- Bio-inspired Engineering
Background:
- Flapping wings generate complex vortical structures crucial for lift generation.
- Previous studies suggested dual leading-edge vortices (LEVs) on flapping wings, but their existence and formation mechanisms remained unclear.
Purpose of the Study:
- To experimentally confirm the existence of dual LEVs on flapping wings.
- To investigate the influence of kinematic and geometric parameters on dual LEV formation and structure.
Main Methods:
- Utilized a scaled-up electromechanical flapping wing model in a water tank.
- Employed dye flow visualization and digital particle image velocimetry (DPIV) for high-resolution flow field analysis.
- Systematically varied wing aspect ratio, angle of attack, and Reynolds number.
Main Results:
- Confirmed the existence of dual LEVs on flapping wings for the first time.
- Observed that dual LEV formation is dependent on high mid-stroke angles of attack and Reynolds numbers, independent of aspect ratio.
- The primary LEV remained attached to the wing, while a secondary, same-sense vortex shed from the outer wing.
Conclusions:
- Dual LEVs are a real phenomenon in flapping wing aerodynamics, resembling those on non-slender delta wings.
- Understanding dual LEV dynamics provides insights into the complex aerodynamics of insect flight.
- The formation of dual LEVs is primarily governed by kinematic and Reynolds number conditions.
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