Active turbulence control technique for drag reduction

Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils

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244130, B64C21/10

Patent

active

059019280

ABSTRACT:
A method of disrupting a turbulent region of a boundary layer within a fluid flow passing over a surface to decrease momentum transfer, and thus friction drag, between the turbulent flow and the surface. Bending waves are generated on the surface to impose velocity and/or pressure oscillations within the turbulent region and disrupt the normal turbulent process within the boundary layer, thereby decreasing the transfer of momentum from the turbulent flow to the surface. The bending waves are preferably generated in a predominantly spanwise or normal direction relative to the streamwise fluid flow. In another embodiment, the bending waves enhance the turbulent process and increase the transfer of momentum between the turbulent flow and the surface. Bending wave actuators may bend the surface to generate bending waves within the surface itself. In another embodiment, actuators may generate bending waves within a separate material attached to the surface. Bending waves may also be generated within a laminar region of the boundary layer to trip the laminar region to turbulent flow and thereby energize the boundary layer.

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