Leaf seal

Patent metadata

Field	Value
Publication number	US-9121506-B2
Application number	US-201414317704-A
Country	US
Kind code	B2
Filing date	Jun 27, 2014
Priority date	Jun 28, 2013
Publication date	Sep 1, 2015
Grant date	Sep 1, 2015

Abstract

This application describes a leaf seal arrangement, including: a first component having a high pressure area and a low pressure area therein; a second component which passes from the high pressure area to the low pressure area; a leaf seal having an array of leaf elements between the high and low pressure areas, each leaf element having a fixed end and a free end, wherein the fixed end is attached to the first component and the free end defines a sealing surface through which the second component sealably passes, a sealing gap therebetween, and wherein the sealing gap generally converges from the high pressure area toward the lower pressure area. Also described is a method of providing a leaf seal.

First claim

The invention claimed is:

1. A leaf seal arrangement, comprising:
a first component having a high pressure area and a low pressure area therein;
a second component which passes from the high pressure area to the low pressure area;
a leaf seal having an array of leaf elements between the high and low pressure areas, each leaf element having a fixed end and a free end, wherein the fixed end is attached to the first component and the free end defines a sealing surface through which the second component sealably passes, a sealing gap therebetween;
wherein the sealing gap generally converges from the high pressure area toward the lower pressure area; and,
wherein the leaf elements have an axial width between the high pressure area and the low pressure area, the convergent portion of the sealing surface extending across between 60% and 100% of the width of the sealing surface.

2. A leaf seal arrangement as claimed in claim 1 , wherein the second component is rotatably mounted relative to the first component and defines a neutral rotational axis, wherein the sealing gap is tapered and the angle of taper is between 1 degree and 20 degrees.

3. A leaf seal as claimed in claim 1 wherein the sealing gap converges at a constant rate.

4. A leaf seal as claimed in claim 1 , wherein the sealing gap includes more than one convergent portions, each portion having different rates of convergence.

5. A leaf seal as claimed in claim 4 , wherein the first portion which extends from the downstream edge of the leaf element and is inclined to the neutral axis by an angle α 1 which is in the range bounded by 1 degree and 30 degrees, and the second portion extends from the first portion and is inclined to the neutral axis by an angle α 2 which is greater than or equal to α 1 and in the range bounded by 1 degree and 30 degrees.

6. A leaf seal as claimed in claim 5 , wherein the profile of the leaf of the first or second portion is not straight and the angles α 1 and α 2 represent lines which extend from the respective upstream and downstream edges of the upstream and downstream portions.

7. A leaf seal as claimed in claim 1 having a downstream portion which is parallel to the surface of the rotating component.

8. A leaf seal as claimed in claim 7 , wherein the downstream portion extends across less than 20% of the axial width of the leaf element.

9. A leaf seal as claimed in claim 1 comprising circumferential portions of convergent sealing gap and circumferential portions of non-convergent sealing gap.

10. A leaf seal as claimed in claim 1 , wherein the convergent sealing gap is at least partially defined by tapered profile on the second component.

11. A leaf seal as claimed in claim 1 , wherein the leaf seal is suitable for use in a gas turbine engine.

12. A gas turbine engine including a leaf seal as claimed in claim 1 .

13. A method of providing a leaf seal for defining a high pressure area and a low pressure area in a first component in which a second component passes from the high pressure area to the low pressure area; the leaf seal having an array of leaf elements, each leaf element having a fixed end and a free end, wherein the fixed end is attached to the first component and the free end defines a sealing surface through which the second component sealably passes, a sealing gap therebetween, and wherein the sealing gap generally converges from the high pressure area toward the lower pressure area, the method comprising:
determining the expected amount of deflection which will be experienced between the first and second components at the sealing gap during normal operation;
determining a required amount of convergence in the sealing gap to accommodate the expected amount of deflection;
configuring either or both of the leaf seal and the second component to provide the required convergence.

14. A method as claimed in claim 13 , wherein the required convergence is greater than the expected deflection.

15. A method as claimed in claim 14 , wherein the sealing gap is configured to provide positive hydrostatic lift under all normal operating conditions.

Assignees

• Rolls Royce Plc

Inventors

• Franceschini Gervas

Classifications

• F02C7/28

  Arrangement of seals · CPC title

• F16J15/3292 Primary

  Lamellar structures · CPC title