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AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsMichael J. Walsh, John B. Anders, Jerry N. Hefner
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The invention is a system of flow control devices which result in reduced skin friction on aerodynamic and hydrodynamic surfaces. The devices cause a breakup of large-scale disturbances in the boundary layer of the flow field. Referring to FIGS. 1 and 2, the riblet device 10 acts to reduce disturbances near the boundary layer wall by the use of longitudinal striations forming vee-shaped grooves. These grooves are dimensional on the order of the wall vortices and turbulent burst dimensions 31 depicted in FIG. 3. The large-eddy breakup device 41, depicted in FIGS. 4 and 5, is a small strip or airfoil which is suspended in the upper region of the boundary layer. Various physical mechanisms cause a disruption of the large-scale vortices. The combination of the devices of this invention result in a substantial reduction in skin friction drag.
A combination of devices to reduce skin friction drag by controlling the flow characteristics of a turbulent boundary layer, such that both vertical and horizontal oscillations in the flow are damped, resulting in a substantial reduction in aerodynamic noise and retarded pressure fluctuations that lead to flutter modes, comprising:
Dependencies are inferred from the claim text.