The leading-edge vortex on a rotating wing changes markedly beyond a certain central body size

Area of Science:

• Fluid dynamics
• Aerodynamics
• Bio-inspired engineering

Background:

• Stable leading-edge vortex (LEV) attachment is critical for high lift generation in rotating wings with central bodies.
• Central body size influences LEV structure via Reynolds number changes and Coriolis acceleration effects.
• Understanding these effects is vital for designing efficient rotating wing systems and comprehending insect flight.

Purpose of the Study:

• To independently investigate the effects of Reynolds number and wing-offset on the leading-edge vortex (LEV) structure of a rotating wing.
• To determine how central body size variations impact LEV stability and morphology.
• To provide insights into the aerodynamic principles governing insect flight.

Main Methods:

• Utilized scanning particle image velocimetry (PIV) to map the three-dimensional leading-edge vortex (LEV) structure.
• Employed a rotating wing model with a central body.
• Carefully validated image acquisition and correlation techniques for accurate flow field reconstruction.

Main Results:

• Leading-edge vortex (LEV) structure is primarily influenced by changes in Reynolds number.
• LEV-split is minimally affected by central body radius variations within a small offset range, relevant to insect flight.
• Significant changes in LEV-split occur beyond this small offset range.

Conclusions:

• Reynolds number is the dominant factor affecting LEV structure in rotating wings.
• The impact of central body size on LEV stability is minimal at small wing offsets, mirroring insect flight conditions.
• Larger wing offsets lead to substantial alterations in LEV behavior, suggesting design implications for artificial rotating wings.