Blade outer air seal with non-linear response

Patent metadata

Field	Value
Publication number	US-10822964-B2
Application number	US-201816189233-A
Country	US
Kind code	B2
Filing date	Nov 13, 2018
Priority date	Nov 13, 2018
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

A blade outer air seal (BOAS) for a gas turbine engine includes a seal ring body having a radially inner face and a radially outer face that axially extend between a leading edge portion and a trailing edge portion and a segmented spline that extends from the radially outer face of the seal ring body, the seal secured to the radially inner face of the seal ring body.

First claim

What is claimed is:

1. A blade outer air seal (BOAS) for a gas turbine engine, comprising:
a full ring hoop seal ring body having a radially inner face and a radially outer face;
a honeycomb seal secured to the radially inner face of the seal ring body adjacent to a turbine rotor; and
a segmented spline that extends radially outward from the radially outer face of the seal ring body, the segmented spline comprises slots to permit communication of a purge airflow between the radially outer face and a turbine exhaust case, a spacing between the segmented spline and a machined pad on the turbine casing set at assembly to provide a tolerance-controlled interface between the BOAS and the turbine casing that sets the non-linear thermal expansion response of the blade outer air seal (BOAS) with respect to the turbine rotor during engine operation
a seal secured to the radially inner face of the seal ring body.

2. The blade outer air seal (BOAS) as recited in claim 1 , further comprising a thermal barrier coating applied to at least a portion of a radially inner face of the seal.

3. The blade outer air seal (BOAS) as recited in claim 1 , wherein the seal is brazed to the radially inner face.

4. The blade outer air seal (BOAS) as recited in claim 1 , wherein the radially inner face and the radially outer face of the seal ring body axially extends between a leading edge portion and a trailing edge portion.

5. The blade outer air seal (BOAS) as recited in claim 4 , wherein the honeycomb seal extends at least partially between the leading edge portion and the trailing edge portion.

6. The blade outer air seal (BOAS) as recited in claim 1 , wherein the segmented spline abuts a power turbine engine casing of a turboshaft engine.

7. A non-linear response system, comprising:
a turbine rotor along an axis;
a turbine exhaust case comprising a pad at least partially around the axis; and
a blade outer air seal (BOAS) with a segmented spline that extends radially outward from a radially outer face of a full hoop seal ring body and a honeycomb seal secured to the radially inner face of the seal ring body adjacent to the turbine rotor, the segmented spline includes slots to permit communication of a purge airflow between the radially outer face and the turbine exhaust case, a spacing between the segmented spline and the pad on the turbine casing set at assembly to provide a tolerance-controlled interface between the BOAS and the turbine casing that sets the non-linear thermal expansion response of the blade outer air seal (BOAS) with respect to the turbine rotor during engine operation.

8. The non-linear response system in claim 7 , wherein the blade outer air seal (BOAS) comprises a honeycomb seal that extends radially inward from the full hoop seal ring body.

9. The non-linear response system in claim 8 , wherein the turbine rotor comprises rotor blades with knife edges that interface with the honeycomb seal.

10. The non-linear response system in claim 7 , wherein the pad is a machined surface.

11. A method of controlling a specific rate of thermal change to match a corresponding blade design with a blade outer air seal (BOAS) for a gas turbine engine, comprising:
setting a spacing between a segmented spline that extends radially outward from a radially outer face of a full hoop seal ring body and a machined pad on a turbine casing at assembly to provide a tolerance-controlled interface between a blade outer air seal (BOAS) and the turbine casing that sets a predefined non-linear thermal expansion response of the blade outer air seal (BOAS) with respect to the turbine rotor;
securing a honeycomb seal to a radially inner face of the seal ring body adjacent to the turbine rotor; and
selectively abutting the segmented spline that extends from the radially outer face of a full hoop seal ring body with the machined pad during engine operation resulting in the non-linear thermal expansion response reducing a tip clearance between the turbine rotor and the honeycomb seal of the blade outer air seal (BOAS).

12. The method as recited in claim 11 , further comprising controlling a purge airflow between the radially outer face and the engine casing.

13. The method as recited in claim 12 , further comprising controlling the airflow through slots in the segmented spline.

14. The blade outer air seal (BOAS) as recited in claim 1 , wherein the pad is machined into the turbine exhaust casing.

15. The blade outer air seal (BOAS) as recited in claim 1 , wherein the honeycomb seal interfaces with a knife edge that extends from a blade tip of the turbine rotor.

16. The blade outer air seal (BOAS) as recited in claim 1 , wherein the segmented spline extends radially outward about 0.04-0.06 inches (1.02-1.5 mm) to provide an assembly gap of 0.005-0.020 inches (0.127-0.508 mm) within the turbine exhaust case which results in a 0.01-0.03 inch (0.025-0.08 mm) running gap during operation.

Assignees

• United Technologies Corp
• Raytheon Tech Corp

Inventors

• Mccaffrey Michael G

Classifications

• F01D25/243

  Flange connections; Bolting arrangements (F01D25/265 takes precedence) · CPC title

• Y02T50/60

  Efficient propulsion technologies, e.g. for aircraft · CPC title

• F01D25/26

  Double casings; Measures against temperature strain in casings · CPC title

• F01D9/04

  forming ring or sector · CPC title

• F05D2240/11

  Shroud seal segments · CPC title