Unsteady Flow and Aerodynamic Effect of a Dynamic Trailing-Edge Flap in Flapping Flight

Flapping-wing mechanism offers unique aerodynamic advantages over conventional flight methods for design of micro air vehicles (MAVs). The inherently unsteady nature of the flapping motion is responsible for the primary force production, and also differentiates flapping wing fliers from conventional fixed and rotary wing configurations. The unsteady aerodynamic phenomena are not only sensitive to variations in the wing motion but also for the dynamic deformed wing surface. Yet, it is not well understood how the unsteady aerodynamic phenomena and dynamic wing morphing interact to modulate flow and to determine overall aerodynamic performance.

In current work, the deformable wing is simplified as a rigid plate hinged with a controllable trailing-edge flap. The leading-edge portion of the plate is driven by a prescribed hovering motion moving in a horizontal stroke plane. The deflection of trailing-edge flap follows a sinusoidal function with respect to the leading-edge for mimicking time-varying camber deformation. Key parameters for determining deformed plate kinematics, such as stroke-to-chord ratio, trailing-edge flap deflection amplitude, and phase shift of trailing-edge deflection, are studied to explore their effects on aerodynamic performance and flow modulation. An in-house immersed boundary method based Direct Numerical Simulation (DNS) solver is used to simulate the unsteady flow. Results from current parametric studies will be used to analyze unsteady force productions due to dynamic trailing-edge flap in flapping flight.