Impacts of Unsteady Flow Environments on the Propulsive Performance of Oscillating Foils

What is it about?

A wide range of animal locomotion, from birds and insects flapping their wings to fish swimming, depends on oscillating or flapping motions for propulsion and maneuver. Most aerodynamic understanding of this propulsive motion comes from testing in steady, low turbulence environments. However, it is known that the natural environment is often highly unsteady. A numerical investigation is conducted to understand the impact of an unsteady incoming air flow on the aerodynamic performance of an oscillating airfoil. This study demonstrates that the presence of unsteadiness in the environment serves to increase thrust production of an oscillating airfoil. It is also shown that in highly unsteady flow environments the thrust of a pitching airfoil is accurately represented as a function of the Reynolds number, Strouhal number, and turbulence intensity. These results may influence the development of innovative unmanned aerial vehicles (UAVs), micro-air vehicles (MAVs), and autonomous underwater vehicles (AUV).

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