Cavity acoustic tones suppression

Patent metadata

Field	Value
Publication number	US-9463754-B2
Application number	US-201414775832-A
Country	US
Kind code	B2
Filing date	Mar 13, 2014
Priority date	Mar 15, 2013
Publication date	Oct 11, 2016
Grant date	Oct 11, 2016

Abstract

A cavity system that tends to increase the thickness ( 28 ) of the shear layer ( 22 ), comprising: a cavity ( 2 ) and a plurality of rods ( 4 ) extending away from the cavity base ( 3 ) to a height extending beyond the leading edge ( 14 ); the rods ( 4 ) being positioned downstream of and in the proximity of the leading edge ( 14 ). The rods ( 4 ) may extend to different heights and/or be positioned longitudinally offset (e.g. in a zig-zag pattern). The rods may be reversibly movable to a configuration in which they are fully enclosed in the cavity ( 2 ) when the cavity ( 2 ) is closed. Flow alteration elements ( 34, 38 ), for example channels ( 34 ) passing through the rods ( 4 ) and/or protrusions ( 38 ) extending from the rod ( 4 ) may be provided on the rods ( 4 ).

First claim

What is claimed is:

1. A cavity system, comprising:
a cavity ( 2 ) and a plurality of rods ( 4 );
the rods ( 4 ) extending in a direction away from a base ( 3 ) of the cavity ( 2 ) to a height that extends beyond the height of a leading edge ( 14 ) of the cavity ( 2 ), the leading edge ( 14 ) being relative to an actual or intended flow direction ( 6 ) of a fluid over the cavity ( 2 );
the rods ( 4 ) being positioned downstream of, and in the proximity of, the leading edge ( 14 ) of the cavity ( 2 );
wherein one or more flow alteration elements ( 34 , 38 ) are provided on one or more of the rods ( 4 );
wherein at least some of the flow alteration elements ( 34 , 38 ) comprise or provide additional edges at the one or more rods ( 4 ) that are in addition to the edge or edges provided by the underlying shape of the rod or rods ( 4 ); and
wherein at least some of the flow alteration elements ( 34 , 38 ) comprise a channel ( 34 ) passing through the rod ( 4 ).

2. The cavity system according to claim 1 , wherein one or more of the rods ( 4 ) extends to a different height to one or more of the other rods ( 4 ).

3. The cavity system according to claim 1 , wherein one or more of the rods ( 4 ) is positioned longitudinally offset with respect to one or more of the other rods ( 4 ).

4. The cavity system according to claim 3 , wherein the longitudinal offset is in the form of a zig-zag pattern.

5. The cavity system according to claim 1 , wherein the rods ( 4 ) are fixed in the cavity ( 2 ) in a manner that allows them to be reversibly moved to a further configuration in which they are fully enclosed in the cavity ( 2 ) when the cavity ( 2 ) is closed.

6. The cavity system according to claim 1 , wherein at least some of the flow alteration elements ( 34 , 38 ) comprise a protrusion ( 38 ) extending from the rod ( 4 ).

7. The cavity system according to claim 1 , wherein at least two different types of flow alteration elements ( 34 , 38 ) are provided.

8. The cavity system according to claim 1 , wherein the rods ( 4 ) are positioned at a distance from the leading edge ( 14 ) that is ≦0.2×the distance between the leading edge ( 14 ) and an aft edge ( 16 ).

9. The cavity system according to claim 8 , wherein the rods ( 4 ) are positioned at a distance from the leading edge ( 14 ) that is ≦0.1×the distance between the leading edge ( 14 ) and the aft edge ( 16 ).

10. The cavity system according to claim 9 , wherein the rods ( 4 ) are positioned at a distance from the leading edge ( 14 ) that is ≦0.05×the distance between the leading edge ( 14 ) and the aft edge ( 16 ).

11. The cavity system according to claim 1 , wherein for one or more of the rods ( 4 ), at least a portion of the rod ( 4 ) slants in the flow direction ( 6 ).

12. The cavity system according to claim 1 , wherein the effect of the rods ( 4 ) is to increase the thickness ( 28 ) of the shear layer ( 22 ).

13. A cavity system, comprising:
a cavity ( 2 ) and a plurality of rods ( 4 );
the rods ( 4 ) extending in a direction away from a base ( 3 ) of the cavity ( 2 ) to a height that extends beyond the height of a leading edge ( 14 ) of the cavity ( 2 ), the leading edge ( 14 ) being relative to an actual or intended flow direction ( 6 ) of a fluid over the cavity ( 2 );
the rods ( 4 ) being positioned downstream of, and in the proximity of, the leading edge ( 14 ) of the cavity ( 2 );
wherein one or more flow alteration elements ( 34 , 38 ) are provided on one or more of the rods ( 4 );
wherein at least some of the flow alteration elements ( 34 , 38 ) comprise or provide additional edges at the one or more rods ( 4 ) that are in addition to the edge or edges provided by the underlying shape of the rod or rods ( 4 ); and
wherein the flow alteration elements ( 34 , 38 ) are at different heights on different rods ( 4 ).

14. The cavity system according to claim 13 , wherein at least two different types of flow alteration elements ( 34 , 38 ) are provided.

15. The cavity system according to claim 13 , wherein the rods ( 4 ) are positioned at a distance from the leading edge ( 14 ) that is ≦0.2×the distance between the leading edge ( 14 ) and an aft edge ( 16 ).

16. The cavity system according to claim 15 , wherein the rods ( 4 ) are positioned at a distance from the leading edge ( 14 ) that is ≦0.1×the distance between the leading edge ( 14 ) and the aft edge ( 16 ).

17. The cavity system according to claim 16 , wherein the rods ( 4 ) are positioned at a distance from the leading edge ( 14 ) that is ≦0.05×the distance between the leading edge ( 14 ) and the aft edge ( 16 ).

18. The cavity system according to claim 13 , wherein for one or more of the rods ( 4 ), at least a portion of the rod ( 4 ) slants in the flow direction ( 6 ).

19. A cavity system, comprising:
a cavity ( 2 ) and a plurality of rods ( 4 );
the rods ( 4 ) extending in a direction away from a base ( 3 ) of the cavity ( 2 ) to a height that extends beyond the height of a leading edge ( 14 ) of the cavity ( 2 ), the leading edge ( 14 ) being relative to an actual or intended flow direction ( 6 ) of a fluid over the cavity ( 2 );
the rods ( 4 ) being positioned downstream of, and in the proximity of, the leading edge ( 14 ) of the cavity ( 2 );
wherein one or more flow alteration elements ( 34 , 38 ) are provided on one or more of the rods ( 4 );
wherein at least some of the flow alteration elements ( 34 , 38 ) comprise or provide additional edges at the one or more rods ( 4 ) that are in addition to the edge or edges provided by the underlying shape of the rod or rods ( 4 );
wherein at least some of the flow alteration elements ( 34 , 38 ) comprise a channel ( 34 ) passing through the rod ( 4 ); and
wherein the flow alteration elements ( 34 , 38 ) are at different heights on different rods ( 4 ).

Assignees

• Bae Systems Plc

Inventors

• Patience David Euan

Classifications

• B64C2230/08

  by influencing fluid flow by means of surface cavities, i.e. net fluid flow is null · CPC title

• B60R13/08 Primary

  Insulating elements, e.g. for sound insulation {(sound insulating linings for trains B61D17/185; drivers' cabs for load-carrying vehicles insulated against vibrations or noise B62D33/0604; thermal or acoustic insulation of engines F02B77/11; damping of sounds using compensation by electro-acoustic methods G10K11/178)} · CPC title

• G10K11/161 Primary

  in systems with fluid flow (G10K11/162 takes precedence; gas flow silencers or exhaust apparatus for machines or engines in general or for internal combustion engine F01N, noise absorbers in pipes or pipe systems F16L55/02; noise absorption in air conditioning and ventilation F24F13/24; silencing exhaust or propulsion jets in aircraft B64D33/06) · CPC title

• B64C23/06

  by generating vortices · CPC title

• G10K11/16

  Methods or devices for protecting against, or for damping, noise or other acoustic waves in general (G10K11/36 takes precedence) · CPC title