# US 8,540,487 B2 · Actuatable seal for aerofoil blade tip

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- Number: US 8,540,487 B2
- Document ID: US8540487B2
- Status: Granted
- Kind: B2
- Application number: 12/817,462
- Filed: 2010-06-17
- Published: 2011-01-06
- Granted: 2013-09-24
- Earliest claimed: 2009-07-01
- Assignees: ROLLS-ROYCE plc
- Applicants: Kristofer J. Bottome; Matthew P. Jevons
- Inventors: Kristofer J. Bottome; Matthew P. Jevons
- Web page: https://patentgrep.com/patent/US8540487B2

## CPC

- F01D 11/22: by mechanically actuating the stator or rotor components, e.g. moving shroud sections relative to the rotor
- F01D 5/20: Specially-shaped blade tips to seal space between tips and stator {(F01D5/225 takes precedence)}
- F01D 11/16: by self-adjusting means (F01D11/12 takes precedence)
- F04D 29/164: {of an axial flow wheel}
- F04D 29/324: {Blades}
- F05D 2240/57: Leaf seals
- F05D 2260/407: through piezoelectric conversion
- Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The present invention relates to an actuatable seal (14) for an aerofoil blade tip, for providing a seal between the blade tip (12) and an adjacent surface (10) over which the blade tip passes in use. The seal comprises a flexible member that is arranged in use to be mounted on the tip of a rotating aerofoil blade and to flex towards the surface under the action of centrifugal force when the blade rotates. The seal further comprises an actuator means provided on the flexible member and operably arranged in use to deflect at least a portion of the flexible member away from the surface.

## Claims

### Claim 1

An actuatable seal for an aerofoil blade tip, for providing a seal between the blade tip and an adjacent surface over which the blade tip passes in use,
the seal comprising:
a flexible member arranged in use to be mounted on the tip of a rotating aerofoil blade and to flex towards the surface under the action of centrifugal force when the blade rotates, and
actuator means provided on the flexible member and operably arranged in use to deflect at least a portion of the flexible member away from the surface.

### Claim 2 (depends on 1)

An actuatable seal according to claim 1, wherein the actuator means is a piezoelectric actuator.

### Claim 3 (depends on 1)

An actuatable seal according to claim 1, wherein the flexible member comprises a membrane attached to a tip of an aerofoil blade along an edge of the membrane.

### Claim 4 (depends on 1)

An actuatable seal according to claim 1, wherein the flexible member comprises a fold or loop of flexible material attached to a tip of an aerofoil blade along at least two edges of the flexible material.

### Claim 5 (depends on 4)

An actuatable seal according to claim 4 wherein the flexible member defines an elongate cavity over the tip of the blade.

### Claim 6 (depends on 5)

An actuatable seal according to claim 5 wherein the flexible member has a plurality of holes through which air, under pressure, is arranged to pass to assist in sealing the gap between the flexible member and the surface.

### Claim 7 (depends on 1)

An aerofoil blade having an actuatable seal according to claim 1.

### Claim 8 (depends on 7)

An aero engine including an aerofoil blade according to claim 7.