2 | MATERIALS AND
METHODS
2.1 | Specimens
Lady beetles, H. axyridis were collected in Suzhou (China) in
August 2023. They were anaesthetized at room temperature using ethyl
ether and killed with an overdose. For investigation of the morphology
of wing cross sections, three right hindwings of male H. axyridiswere cut through at the wing base and removed from their bodies.
2.2 | Corrugated airfoil
The right hindwing of H. axyridis was cut into nine sections
transversely along chordal direction using a scalpel. Each
cross-sectional profile position was recorded as l/L withl being the distance between the cross section and the wing base,
and L being the total wing length. The cross-sectional chord was
denoted as c . Furthermore, the reference velocityvr was taken to be 1 m/s. The air densityρ was taken to be 1.225 kg/m3 and the air
viscosity \(\mu\) was taken as 1.7894×10-5 Pa·s. The
Reynolds number for these cases was calculated asRe=ρυrc /μ . As shown in Figure1(a), theRe with the l /L length between 0.1 and 0.8 is greater than
102, and the higher Re range is between 0.2 and
0.6. So, the cross sections 0.2, 0.4, and 0.6 are selected to research.
Three selected cross sections are shown in Figure 1(b). These cut of
cross section were horizontal and smooth. Morphologies of cross sections
were observed by the 3D microscope system (VHX-6000, Keyence, Japan), as
show in Figure 1 (c). The geometry profile models of the three 2D
corrugated airfoils (CA model) were established through the combination
of hand-held probe three-coordinate measuring instrument (XM-T1200,
Keyence, Japan) and AutoCAD software, including airfoil profile 1 (AP1),
airfoil profile 2 (AP2) and airfoil profile 3 (AP3), as shown in Figure
1(d) and 1(e).