Variable area flow duct employing secondary flows, and method therefor
First Claim
1. A flow duct comprising:
- a circumferential wall having an inner surface, the inner surface defining a fluid flow path for a primary flow flowing through the flow duct; and
at least one curving projection forming a non-moveable vane, and formed to project from the circumferential wall of the inner surface of the flow duct such that the non-moveable vane projects radially inwardly toward an axial center of the flow duct and non-parallel to a longitudinal centerline extending along the axial center of the flow duct, the non-moveable vane for generating a secondary flow adjacent the inner surface that effectively reduces an internal cross-sectional area of the duct for said primary flow.
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Accused Products
Abstract
A variable area flow duct and method. In one embodiment the flow duct includes a plurality of helical vanes arranged around an interior surface wall of the flow duct. The vanes cause secondary flow vortices to be developed in the vicinity of each of the vanes that effectively reduce the interior cross-sectional area of the duct that a primary flow sees as it flows through the duct. In various embodiments fluidic injection is employed to suppress the formation of the secondary flow vortices during certain phases of operation, for example, during an afterburn phase of operation of a jet aircraft engine which the flow duct is being used with. In another embodiment, an ablative coating is used over the vanes to suppress the formation of the secondary flow vortices. The ablative material is removed by the hot fluid flow during an afterburn phase of operation, thus exposing the vanes and enabling the subsequent formation of secondary flow vortices to narrow the cross-sectional area of the throat.
21 Citations
24 Claims
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1. A flow duct comprising:
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a circumferential wall having an inner surface, the inner surface defining a fluid flow path for a primary flow flowing through the flow duct; and at least one curving projection forming a non-moveable vane, and formed to project from the circumferential wall of the inner surface of the flow duct such that the non-moveable vane projects radially inwardly toward an axial center of the flow duct and non-parallel to a longitudinal centerline extending along the axial center of the flow duct, the non-moveable vane for generating a secondary flow adjacent the inner surface that effectively reduces an internal cross-sectional area of the duct for said primary flow. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 21, 22)
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9. A flow duct comprising:
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a circumferential wall having an inner surface, the inner surface defining a fluid flow path of a primary flow flowing through the flow duct; a plurality of non-moveable vanes extending radially inwardly toward an axial center of the flow duct from said inner surface of the circumferential wall, and further such that said non-moveable vanes extend non-parallel to a longitudinal centerline of the flow duct, the non-moveable vanes generating a plurality of secondary flows adjacent the inner surface that reduce an internal cross-sectional area of the flow duct for said primary flow; and a plurality of fluid jets controllably injected through openings in said circumferential wall adjacent said non-moveable vanes, for suppressing the formation of said secondary flows. - View Dependent Claims (10, 11, 12, 13, 23)
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14. A method for controlling a flow of a fluid flowing through a duct, comprising:
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forming a non-moveable vane on an interior circumferential wall of said duct such that said non-moveable vane projects radially inwardly toward an axial center of said duct and non-parallel to a longitudinal centerline of said duct; flowing a fluid through said duct to form a primary flow; and using said non-moveable vane to form a secondary flow adjacent said non-moveable vane, said secondary flow causing a reduction of an effective cross sectional area within said duct for said primary flow. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A mobile platform comprising:
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an engine; an exhaust nozzle operably associated with said engine to receive a primary fluid flow from said engine; said exhaust nozzle having a circumferential inner surface, the circumferential inner surface defining a fluid flow path for said primary flow; and a plurality of non-moveable vanes extending from said circumferential inner surface radially inwardly toward an axial center of said exhaust nozzle, and non-parallel to a longitudinal centerline of said exhaust nozzle, for generating a plurality of secondary flows adjacent said circumferential inner surface that effectively reduce an internal cross-sectional area of said exhaust nozzle for said primary flow.
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24. The method 14, wherein the non-moveable vane is formed so as to extend non-parallel to a longitudinal axis of the duct.
Specification