Unsteady Low Reynolds Number Aerodynamics for Micro Air Vehicles (MAVs)

摘要

This work introduces the Micro Air Vehicle (MAV) problem from the viewpoint of aerodynamics. Water tunnels are assessed as tools for MAV aerodynamics. The design, construction and instrumentation of RB's 'Horizontal Free-surface Water Tunnel' is documented. Experiments in steady aerodynamics at low Reynolds number for airfoils, plates and wings of various planforms are mentioned, with focus on laminar to turbulent transition and documentation of how Reynolds number, flowfield conditions and model geometry interplay to affect laminar separation and possible turbulent reattachment, and how planform effects impact lift generation. Passing to the unsteady aerodynamics problem, the HFWT's 'High-Intensity Pitch-Plunge Oscillator' Rig is described. Then, the bulk of the report focuses on experiments in unsteady aerodynamics. A broad range of periodic and transient problems is covered, anchored in traditional problems of airfoil dynamic stall, and expanding to MAV applications of perching and flapping. New knowledge includes elucidation of the surprisingly broad limits of linear superposition in markedly nonlinear problems, and notes on the relative importance of laminar to turbulent transition in a broad range of unsteady problems.