Phase II Final Report - NASA's Institute for Advanced Concepts

Chapter 3.0 Vehicle Design
3.3 Wing Aerodynamics
Figure 3-27: CAD Wing Section for the Hollow, Tapered Baseline Geometry--Leading
Edge View
3.3 Wing Aerodynamics
3.3.1 Computational Fluid Dynamics
3.3.1.1 Introduction
Low Reynolds number, unsteady aerodynamics of thin cambered wings is of current interest
because of technological applications such as micro air vehicles (MAV). High lift associated
with insect flight, not predicted by conventional quasi-steady aerodynamics, has been a fascinating
subject for many researchers. Several mechanisms, such as the “clap-and-fling” (Weis-Fogh
mechanism) and the “delayed-stall-rotational-lift-wake-capture” (Dickinson mechanism), have
been proposed to explain how lift is generated during the cyclic motion of the insect wing. Forward
flight, requiring both lift and thrust, has been more easily analyzed than hovering flight.
Studies on tethered live animals have been conducted to measure forces and visualize flow patterns.
Experimental studies using models with basic wing kinematics, such as heaving, flapping,
and pitching, have also been undertaken [115, 129]. Gaining a thorough understanding of insect
wing aerodynamics and incorporating their desirable features into MAV design have become
one of the critical technologies of MAV development.
In this work, we use computational fluid dynamics (CFD) tools to simulate low Reynolds number,
unsteady aerodynamics that incorporate geometries and kinematics representative of insect
wings. Leading edge vortex (LEV) dynamics, span-wise flow features, and dynamic camber
variation during the wingbeat are of particular interest. CFD is an extremely powerful tool for
flow field visualization and provides a tremendous amount of data on the flow field (e.g., lift,
drag). It is especially useful for simulating environments that are either too dangerous or too
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