Patent ID: 8714945

Claim:
A method for controlling air flow over an aerodynamic surface of an airfoil comprising the step of oscillating or pulsing an air jet through an orifice opening in the aerodynamic surface of the airfoil with a controllable, ultra-low friction air pump positioned adjacent to the orifice opening, the air pump having: an air pump housing including a hollow space with an interior surface coated with a film of ultra-low friction amorphous carbon having a thickness of approximately 0.5 to 10 microns; a substantially rigid and flat movable piston made substantially of composite materials and positioned within the air pump housing to be slidable against the interior surface, the piston being substantially symmetric in terms of its mass about a plane extending perpendicularly through a mid-point of the air pump housing; the piston connected to a first shaft element defining an axis of travel and traveling within at least one bushing coated with the ultra-low friction film of amorphous carbon, the piston being thin relative to the axis of travel and the air pump housing, the axis of travel extending in a direction that intersects the aerodynamic surface of the airfoil substantially normally so that the piston oscillates through a neutral centered position along the axis of travel, and the combination of the piston and the first shaft element within the hollow space defining a compression chamber open to an exterior of the aerodynamic surface of the airfoil effective for aerodynamic flow control, whereby the piston, shaft and housing effectively cooperate in operation of the air pump in an ultra-low friction manner of aerodynamic flow control.