Acoustic damper

• US 20060207259A1
• Filed: 10/27/2005
• Published: 09/21/2006
• Est. Priority Date: 11/24/2004
• Status: Active Grant

• Current Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Inventors: MacQuisten, Michael A., Holt, Alistaire S., Whiteman, Michael, Moran, Anthony J.
• Granted Patent: US 7,549,290 B2
• Time in Patent Office: Days
• US Class Current: 60/772
• CPC Class Codes: F01N 1/00 Silencing apparatus characterised by method of silencing by cooling F01N3/02; using liquids F01N3/04
• CPC Class Codes: F23M 20/005 Noise absorbing means
• CPC Class Codes: F23M 5/085 using air or other gas as the cooling medium
• CPC Class Codes: F23R 2900/00014 Reducing thermo-acoustic vibrations by passive means, e.g. by Helmholtz resonators silence apparatus using resonance F01N1/023
• CPC Class Codes: F23R 3/002 Wall structures F23R3/02 and F23R3/007 take precedence
• CPC Class Codes: F23R 3/06 Arrangement of apertures along the flame tube

Abstract

A combustor wall of a gas turbine engine is provided with an acoustic damper component. The component has a first metering passage, a first damping chamber, a first damping passage, a second damping chamber and a second damping passage. Air flows through the damper to be ejected into the combustion chamber from the second damping passage at a selected velocity and volumetric flow. The flow being sufficient to damp instabilities from the combustion process.

Claims

1. An acoustic damper component for a combustor, comprising:

a wall having n through-holes for the passage of fluid therethrough, where n>

2, the acoustic damper further having isolating means arranged to isolate a selected number m of the through-holes from the plurality of through-holes, wherein m>

1 and <

n; and

characterised in that the isolating means comprising at least one metering passage communicating with the m isolated through-holes via a first damping chamber and a second damping chamber.

2. An acoustic damper component according to claim 1, wherein the isolating means further comprises a damping passage connecting the first damping chamber with the second damping chamber.

3. An acoustic damper component according to claim 1, wherein the wall has a thickness between 1 mm and 3 mm.

4. An acoustic damper component according to claim 1, wherein the damping passage has a length between 1 mm and 3 mm.

5. An acoustic damper component according to claim 1, wherein the wall is substantially planar and the damping passage extends parallel thereto.

6. An acoustic damper component according to claim 1, wherein the wall defines at least part of a combustor for a gas turbine engine.

15. A method of damping the amplitude of acoustic frequencies below 1000 Hz in a gas turbine combustor comprising the steps of providing the combustor with an acoustic damper according to claim 1 and passing a flow of fluid through the metering passage, the first damping chamber, the second damping chamber and the m isolated through-holes.

16. A method according to claim 15, wherein the volume of the first damping chamber is below that necessary to generate Helmholtz resonance at frequencies below 1000 Hz.

17. A method according to claim 15, wherein the volume of the second damping chamber is below that necessary to generate Helmholtz resonance at frequencies below 1000 Hz.

18. A method according to claim 15, wherein the flow rate of fluid through the isolated through holes is below 20 m/s.

7. A combustor having an outer wall having a plurality of outer through-holes;

and a co-axial inner wall comprising a plurality of n inner through holes, where n>

2;

isolating means isolating a selected number m of the inner through-holes from the plurality of n through-holes, wherein m>

1 and <

n;

the isolating means comprising at least one metering passage communicating with the m isolated through-holes via a first damping chamber (104) and a second damping chamber;

the outer through-holes being arranged to, in use, supply air to the inner through-holes; and

to the isolated inner through-holes through the metering passage.

8. A combustor according to claim 7, wherein the inner wall and outer wall are separated by pedestals.

9. A combustor according to claim 7, wherein the inner wall and outer wall enclose a cavity, the isolating means being located within the cavity.

10. A combustor according to claim 7, wherein a heat resistant combustor tile provides the inner wall.

11. A combustor according to claim 10, wherein the heat resistant combustor tile is attached to the outer wall by a releasable fastener.

12. A combustor according to claim 11, wherein the releasable fastener is a nut and bolt arrangement.

13. A combustor according to claim 7, wherein the combustor has an axis and a radius extending from the axis, the inner through-holes being arranged at an angle to both the combustor axis and the radial direction.

14. A combustor according to claim 7, wherein the combustor has a circumference, the inner through-holes being angled circumferentially.