Flow outlet

Patent metadata

Field	Value
Publication number	US-9964114-B2
Application number	US-201414563516-A
Country	US
Kind code	B2
Filing date	Dec 8, 2014
Priority date	Dec 23, 2013
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A noise attenuation panel for a bleed flow is presented that causes a total pressure loss of the bleed flow before it is exhausted. The total pressure loss results from at least two regions in which the flow area contracts and then rapidly expands, with the rapid expansion causing mixing and turbulence rather than full total pressure recovery. This reduced pressure means that when the flow is exhausted into a flow (which may be the bypass flow of a gas turbine engine), its energy, and thus its noise, are reduced.

First claim

I claim:

1. A noise attenuation panel for a gas turbine engine comprising:
a plurality of flow passages, wherein:
each flow passage comprises a flow inlet and a flow outlet and changes direction at least once between the flow inlet and the flow outlet;
a flow area through the flow passage increases downstream of the flow inlet and decreases into the flow outlet;
a flow area of the flow outlet is bigger than a flow area of the flow inlet;
the flow inlets form a first planar surface and the flow outlets form a second planar surface offset from the first planar surface;
the noise attenuation panel has a longitudinal axis that passes through a center of the noise attenuation panel and is perpendicular to the first planar surface or the second planar surface;
the noise attenuation panel has a plane extending along the longitudinal axis and along a centerline of the noise attenuation panel; and
the noise attenuation panel is achiral with respect to the longitudinal axis within the plane.

2. The noise attenuation panel according to claim 1 , wherein the flow area through each flow passage increases by at least 25% downstream of the flow inlet within a distance of 2 mm from the flow inlet.

3. The noise attenuation panel according to claim 1 , wherein each flow passage is in the same direction at the flow inlet and the flow outlet.

4. The noise attenuation panel according to claim 1 , wherein each flow passage comprises three changes of direction between the flow inlet and the flow outlet.

5. The noise attenuation panel according to claim 1 , wherein each flow outlet is offset from the flow inlet in a direction perpendicular to the longitudinal axis.

6. The noise attenuation panel according to claim 1 , the noise attenuation panel comprising a stiffening rib that extends perpendicularly to the longitudinal axis and along the centerline of the noise attenuation panel, wherein the noise attenuation panel is symmetrical about the plane, wherein the plane passes through the centre of the stiffening rib.

7. A bleed flow discharge device for discharging a bleed flow taken from a core flow through a core of a gas turbine engine, the bleed flow discharge device comprising:
a bleed flow duct through which, in use, the bleed flow taken from the core flow passes; and
the noise attenuation panel according to claim 1 , the noise attenuation panel being located within the bleed flow duct, such that the bleed flow passes through the noise attenuation panel before exiting from the bleed flow discharge device.

8. The bleed flow discharge device according to claim 7 , the bleed flow discharge device having an inlet and an outlet, and further comprising a bleed flow outlet panel at the outlet through which, in use, the bleed flow exits the bleed flow discharge device.

9. The bleed flow discharge device according to claim 8 , wherein the bleed flow outlet panel comprises:
a perimeter edge that fits within the outlet of the bleed flow discharge device and is formed around a major axis of the bleed flow outlet panel; and
a plurality of exit passages, the plurality of exit passages being formed in at least two distinct regions of the bleed flow outlet panel, each region comprising a plurality of adjacent exit passages, wherein
the plurality of adjacent exit passages in a first region are arranged to direct the bleed flow, in use, in a direction that is substantially aligned with the major axis of the bleed flow outlet panel; and
the plurality of adjacent exit passages in a second region are arranged to direct the bleed flow, in use, in a direction that, when projected onto a plane perpendicular to the major axis and containing the perimeter edge, points towards the closest point on the perimeter edge.

10. The bleed flow discharge device according to claim 9 , arranged for use with a turbofan gas turbine engine having a bypass duct arranged around the core of the turbofan gas turbine engine, the bypass duct having a bypass flow passing therethrough in use, wherein the plurality of exit passages are arranged to discharge the bleed flow into the bypass duct and the second region of the bleed flow outlet panel is generally downstream of the first region relative to the direction of the bypass flow in use.

11. The bleed flow discharge device according to claim 8 , wherein the bleed flow outlet panel and the noise attenuation panel are a single unit, with the flow outlets of the plurality of flow passages of the noise attenuation panel forming inlets to the plurality of exit passages of the bleed flow outlet panel.

12. A bleed flow outlet unit arranged to attenuate noise and direct bleed flow taken from a core flow through a core of a gas turbine engine, the bleed flow outlet unit being a unitary part comprising:
a noise attenuation portion comprising the noise attenuation panel according to claim 1 ; and
a bleed flow outlet portion, wherein
the bleed flow outlet portion comprises bleed flow outlet passages; and
each flow passage of the plurality of flow passages of the noise attenuation portion is fluidly connected to a single respective bleed flow outlet passage such that each flow passage of the plurality of flow passages of the noise attenuation portion forms a continuous flow passage with its single respective bleed flow outlet passage.

13. A turbofan gas turbine engine comprising:
a core engine through which a core flow passes in use;
a bypass duct surrounding the core engine and through which a bypass flow passes in use; and
a bleed flow assembly for allowing a bleed flow to be selectively bled from the core flow to the bypass flow in use, the bleed flow assembly comprising:
a bleed valve in communication with the core flow and arranged to be selectively openable to allow bleed flow to be bled from the core flow; and
the noise attenuation panel according to claim 1 , wherein:
the noise attenuation panel is arranged downstream of the bleed valve relative to the bleed flow, such that, in use, bleed flow that selectively bled from the core flow through the bleed valve passes through the noise attenuation panel before being discharged into the bypass flow.

Assignees

• Rolls Royce Plc

Inventors

• Taylor-Tibbott Oliver C

Classifications

• Y10T29/49323

  Assembling fluid flow directing devices, e.g., stators, diaphragms, nozzles · CPC title

• F05B2260/964

  by damping means · CPC title

• F02C7/045

  having provisions for noise suppression · CPC title

• F05D2210/33

  Turbulent flow · CPC title

• F02K3/075 Primary

  controlling flow ratio between flows · CPC title