Radar energy absorbing deformable low drag vortex generator

Patent metadata

Field	Value
Publication number	US-2017137115-A1
Application number	US-201615227921-A
Country	US
Kind code	A1
Filing date	Aug 3, 2016
Priority date	Dec 31, 2012
Publication date	May 18, 2017
Grant date	—

Abstract

A family of Radar energy Absorbing Deformable Low Drag Vortex Generators (RAD-LDVG) is described herein. This family of devices are fabricated in such a way that it can conform to aircraft surface features while reducing radar returns from structural details. Vortex generators (VGs) are typically used to reattach or smooth gross flowfields over aircraft surfaces. By doing so, an airfoil or wing can maintain attached flow at higher angles of attack and/or higher lift coefficients than one without the VGs. These devices are also used to reattach and/or smooth flows that encounter crossflow-induced instabilities and/or adverse pressure gradients on the upper surfaces of wings or near aircraft boattails. Other uses include reduction of buffet, vibration, flutter, cavity resonance or general bluff-body pressure drag reduction. Although conventional rigid VGs do generate vortical aerodynamic structures, two major problems are often experienced: i.) the inability to conform to curved surfaces, ii.) the generation of radar cross-section spikes produced by the VGs themselves.

First claim

What is claimed is:

1 . A device which is shaped so as to produce stream-wise vortices when attached to a surface exposed to airflow, comprising:
a vortex generator having an upstream end and a distal downstream end, where the vortex generator has a lateral width and a vertical height and a flexible bottom surface configured to mount on a non-uniform surface exposed to airflow where the vertical height of the vortex generator is tapered to increase from the upstream end to the distal downstream end forming a concave upper surface, the concave upper surface having an apex peak at the distal downstream end, and where the lateral width of the vortex generator is tapered to decrease from the upstream end to the distal downstream end forming concave sidewalls; and said vortex generator constructed of a material sufficiently flexible to deform responsive to increased pressure from a flow field to thereby reduce said vortex generators vertical height at the apex peak from an initial height to a reduced height.

2 . The device as recited in claim 1 , conformed to one of a raised surface raised above and a recessed surface recessed below the non-uniform surface.

3 . The device as recited in claim 1 , constructed of material sufficiently flexible to possess a yield strain of greater than 0.5%.

4 . The device as recited in claim 1 , constructed of a material having an averaged electrical resistivity of greater than approximately 1×10 −8 Ω-m, but less than approximately 1×10 10 Ω-m.

5 . The device of claim 1 , constructed of a flexible bulk radar-absorbent material.

6 . The device of claim 1 , constructed of layers of one of radar absorbent and radar-reflective material which form internal Jaumann absorbers.

7 . The device of claim 1 , having an internal structure comprising radar absorbing and radar reflecting microstructures forming radio frequency wedge traps.

8 . The device of claim 1 , wherein the bottom surface is one of concave, flat and hollow, thereby allowing for attachment to the non-uniform surface and accommodating of structural details which lie on the non-uniform surface.

9 . The device of claim 1 , where the device is constructed of a RADAR absorbing material and internally structurally arranged such that an outermost surface is semi dielectric and an internal portion is constructed of semi conductive material.

10 . The device of claim 25 , overlapping the distal downstream end over the upstream end.

11 . A device which is shaped so as to produce stream-wise vortices when attached to a surface exposed to airflow, comprising:
a vortex generator having an upstream end and a distal downstream end, where the vortex generator has a lateral width and a vertical height and a flexible bottom surface configured to mount a non-uniform surface exposed to airflow where the vertical height of the vortex generator is tapered to increase from the upstream end to the distal downstream end forming a concave upper surface, the concave upper surface having an apex peak at the distal downstream end, and where the lateral width of the vortex generator is tapered to decrease from the upstream end to the distal downstream end forming concave sidewalls; and said vortex generator is constructed of a RADAR absorbing material and internally structurally arranged such that an outermost surface is semi dielectric and an internal portion is constructed of semi conducive material.

12 . The device of claim 11 where the flexibility of the material is such that the vertical height reduces as a dynamic pressure of the flow field increases.

13 . The device as recited in claim 11 , constructed of material sufficiently flexible to possess a yield strain of greater than 0.5%.

14 . The device as recited in claim 11 , constructed of a material having an averaged electrical resistivity of greater than approximately 1×10 −8 Ω-m, but less than approximately 1×10 10 Ω-m.

15 . The device of claim 11 , constructed of a flexible bulk radar-absorbent material.

16 . The device of claim 11 , constructed of layers of one of radar absorbent and radar-reflective material which form internal Jaumann absorbers.

17 . The device of claim 11 , having an internal structure comprising radar absorbing and radar reflecting microstructures forming radio frequency wedge traps.

18 . The device of claim 11 , wherein the bottom surface is one of concave, flat and hollow, thereby allowing for attachment to the non-uniform surface and accommodating of structural details which lie on the non-uniform surface.

19 . The device of claim 11 , fabricated into one of a group of several form factors including a vane, a reverse wedge, a wishbone, an asymmetric tetrahedral wedge and any other form factor which generate a streamwise vortices.

20 . The device of claim 11 , overlapping the distal downstream end over the upstream end.

21 . A device which is shaped so as to produce stream-wise vortices when attached to a surface exposed to airflow, comprising:
a vortex generator having an upstream end and a distal downstream end, where the vortex generator has a lateral width and a vertical height and a flexible bottom surface integrally conformed with a non-uniform surface exposed to airflow where the vertical height of the vortex generator is tapered to increase from the upstream end to the distal downstream end forming a concave upper surface, the concave upper surface having an apex peak at the distal downstream end, and where the lateral width of the vortex generator is tapered to decrease from the upstream end to the distal downstream end forming concave sidewalls; and said vortex generator constructed of a material sufficiently flexible to deform responsive to increased pressure from a flow field to thereby reduce said vortex generators vertical height at the apex peak from an initial height to a reduced height.

22 . The device as recited in claim 21 , constructed of material sufficiently flexible to possess a yield strain of greater than 0.5%.

23 . The device as recited in claim 21 , conformed to one of a raised surface raised above and a recessed surface recessed below the non-uniform surface.

24 . The device as recited in claim 21 , constructed of a material having an averaged electrical resistivity of greater than approximately 1×10 −8 Ω-m, but less than approximately 1×10 10 Ω-m.

25 . The device of claim 21 , constructed of a flexible bulk radar-absorbent material.

26 . The device of claim 21 , constructed of layers of one of radar absorbent and radar-reflective material which form internal Jaumann absorbers.

27 . The device of claim 21 , where the concave upper surface is one of smooth and corrugated.

28 . The device of claim 21 , where the sidewalls is one of smooth and corrugated.

29 . The device of claim 21 , further including a plurality of vortex generators arranged linearly upstream end to distal downstream end.

30 . The device of claim 21 , overlapping the distal downstream end over the upstream end.

Assignees

• Univ Kansas

Inventors

• Barrett Ronald M

Classifications

• B64C21/02

  by use of slot, ducts, porous areas or the like · CPC title

• G03G13/283

  obtained by a process including the transfer of a tonered image, i.e. indirect process · CPC title

• H01Q17/008

  with a particular shape (H01Q17/007 takes precedence) · CPC title

• G03G13/26

  for the production of printing plates for non-xerographic printing processes · CPC title

• F15D1/004 Primary

  oriented essentially parallel to the direction of flow · CPC title