Back to results
US 5,803,409 AGranted
Method and apparatus for reducing the drag of flows over surfaces
AssigneeNielsen Engineering & Research, Inc.
InventorLaurence R. Keefe
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeNielsen Engineering & Research, Inc.
InventorLaurence R. Keefe
Estimating the term…
An apparatus, and its accompanying method, for reducing the drag of flows over a surface includes arrays of small disks and sensors. The arrays are embedded in the surface and may extend above, or be depressed below, the surface, provided they remain hydraulically smooth either when operating or when inactive. The disks are arranged in arrays of various shapes, and spaced according to the cruising speed of the vehicle on which the arrays are installed. For drag reduction at speeds of the order of 30 meters/second, preferred embodiments include disks that are 0.2 millimeter in diameter and spaced 0.4 millimeter apart. For drag reduction at speeds of the order of 300 meters/second, preferred embodiments include disks that are 0.045 millimeter in diameter and spaced 0.09 millimeter apart. Smaller and larger dimensions for diameter and spacing are also possible. The disks rotate in the plane of the surface, with their rotation axis substantially perpendicular to the surface. The rotating disks produce velocity perturbations parallel to the surface in the overlying boundary layer. The sensors sense the flow at the surface and connect to control circuitry that adjusts the rotation rates and duty cycles of the disks accordingly. Suction and blowing holes can be interspersed among, or made coaxial with, the disks for creating general three-component velocity perturbations in the near-surface region. The surface can be a flat, planar surface or a nonplanar surface, such as a triangular riblet surface. The present apparatus and method have potential applications in the field of aeronautics for improving performance and efficiency of commercial and military aircraft, and in other industries where drag is an obstacle, including gas and oil delivery through long-haul pipelines.
An apparatus for actively controlling a boundary layer over a surface comprising at least one actuator at scales less than a local boundary layer thickness positioned in a surface, the at least one actuator having a stationary part and a rotating part, wherein the rotating part rotates in the plane of the surface, wherein the rotating part has an axis of rotation that is substantially perpendicular to the surface, and wherein the at least one actuator is either embedded in the surface, or may extend above or be depressed below the surface to the extent it remains hydraulically smooth.
An apparatus for actively controlling a boundary layer over a surface comprising at least one actuator positioned in a surface, the at least one actuator having a stationary part and a rotating part, wherein the rotating part rotates in the plane of the surface, wherein the rotating part has an axis of rotation that is substantially perpendicular to the surface, and wherein the at least one actuator is either embedded in the surface, or may extend above or be depressed below the surface to the extent it remains hydraulically smooth, and further comprising at least one sensor positioned in the surface for sensing flow generated at the surface and connected to control and drive means for adjusting rotation rates and cycles of the at least one actuator.
An apparatus for actively controlling a boundary layer over a surface comprising at least one actuator positioned in a surface, the at least one actuator having a stationary part and a rotating part, wherein the rotating part rotates in the plane of the surface, wherein the rotating part has an axis of rotation that is substantially perpendicular to the surface, and wherein the at least one actuator is either embedded in the surface, or may extend above or be depressed below the surface to the extent it remains hydraulically smooth, and wherein the at least one actuator is multiple arrays of actuators distributed over a surface underlying a boundary layer to be controlled, and further comprising multiple sensors positioned in the surface and connected by control and drive means to the actuators.
An apparatus for actively controlling a boundary layer over a surface comprising at least one actuator Positioned in a surface, the at least one actuator having a stationary part and a rotating part, wherein the rotating part rotates in the plane of the surface, wherein the rotating part has an axis of rotation that is substantially perpendicular to the surface, and wherein the at least one actuator is either embedded in the surface, or may extend above or be depressed below the surface to the extent it remains hydraulically smooth, an wherein the at least one actuator is multiple arrays of actuators distributed over a surface underlying a boundary layer to be controlled, and the arrays are lines of actuators rotating in unison and wherein the sense of rotation of a line of actuators is opposite to that of the lines of actuators on either side of it.
A method for actively controlling a boundary layer over a surface comprising the steps of embedding at least one actuator at scales less than a local boundary layer thickness having at least one rotor in a surface such that the actuator remains hydraulically smooth, rotating the at least one rotor and generating normal vorticity at the surface through the rotating of the at least one rotor.
A method for actively controlling a boundary layer over a surface comprising the steps of embedding at least one actuator having at least one rotor in a surface such that the actuator remains hydraulically smooth, rotating the at least one rotor and generating normal vorticity at the surface through the rotating of the at least one rotor, and further comprising the steps of sensing the normal vorticity generated by the rotating of the at least one rotor, comparing a sensed vorticity with a desired vorticity value and adjusting rotation of the at least one rotor.
Dependencies are inferred from the claim text.