Airfoil thrust augmentation by symmetric heaving motion

I once read somewhere (can't remember where though....) that a simple periodic heaving motion (i.e. oscillations perpendicular to the line of motion) of a wing in forward flight results in some extra thrust. Well, now I believe it ;-) Looking at the forces over the body one may see that this is caused by augmentation of the leading edge suction force. On average though there is no extra lift. Observe also how the wake dipoles (nice huh) have their axes tilted backward a little in reaction to the thrust produced. The axes of the wake dipoles tells you something about direction of the reaction force on the aerofoil.

Category:

Education

Tags:

• airfoil
• aerofoil
• panel method
• inviscid
• fluid dynamics
• potential flow
• Laplace
• incompressible
• wing
• lift
• Kutta condition
• circulation
• vortex panel
• angle of attack
• wake
• unsteady
• flapping
• Kelvin theorem