Device and method for reducing aircraft noise
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsCraig L. Streett, John C. Lin
Life of this patent
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Abstract
A noise abatement device that is positioned adjacent to a body. The noise abatement device generally includes tabs or cavities which thicken the shear layer created by fluid flow over, around, or near the body, by creating horseshoe-shaped vortices; this thickening of the shear layer reduces the strength of fluctuations in the flow which produce noise.
Claims20
A method of abating noise caused by a shear layer, the shear layer created by a fluid flow near an end of a body having a streamwise chord defined as being parallel to the fluid flow wherein the end of the body extends along a direction that is substantially parallel to the streamwise chord, the body further having a lift surface, said method comprising the step of:
- thickening the shear layer adjacent and along the end of the body by creating cross-stream mixing of the shear layer at positions on the lift surface along the end of the body.
A noise abatement device comprising:
- a body having an end, a suction surface, a lift surface, and a streamwise chord defined as being parallel to a fluid flow passing over the body wherein the end extends along a direction that is substantially parallel to the streamwise chord;
- and
- a shear layer thickening element positioned at a plurality of positions on the lift surface adjacent and along the end of the body to create cross-stream mixing of the shear layer at said plurality of positions.
A noise abatement device used to reduce airframe noise, comprising:
- an airfoil having a streamwise chord, a first airfoil end and a second airfoil end opposing one another wherein each of the first airfoil end and second airfoil end extend along a direction that is substantially parallel to the streamwise chords a suction surface, a lift surface, and a trailing edge;
- and
- a retractable flap positioned adjacent the trailing edge of the airfoil, the flap having a first flap end lateral one of the first airfoil end and the second airfoil end, a second flap end, a flap suction surface, and a flap lift surface;
- and
- a plurality of tabs positioned on the lift surface of the airfoil between the first airfoil end and the second airfoil end, along, parallel and adjacent to the first flap end to create cross-stream mixing of the shear layer at said plurality of tabs.
Dependencies are inferred from the claim text.