BLADE TIP CLEARANCE SYSTEMS

• US 20160312643A1
• Filed: 11/19/2014
• Published: 10/27/2016
• Est. Priority Date: 12/10/2013
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Davis, Timothy M., Paulino, Jose R., Duguay, Brian
• Granted Patent: US 10,323,535 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F01D 11/18 using stator or rotor components with predetermined thermal response, e.g. selective insulation, thermal inertia, differential expansion
• CPC Class Codes: F01D 11/24 by selectively cooling-heating stator or rotor components
• CPC Class Codes: F01D 5/02 Blade-carrying members, e.g. rotors rotors of non-bladed type F01D1/34; stators F01D9/00 ; selecting particular materials F01D5/28
• CPC Class Codes: F01D 5/12 Blades specially adapted for radial flow machines or engines F01D5/04; blade roots F01D5/30; rotors with blades adjustable in operation F01D7/00; stator blades F01D9/02
• CPC Class Codes: F05D 2220/32 in gas turbines
• CPC Class Codes: F05D 2260/22141 using fins or ribs
• CPC Class Codes: F05D 2300/5021 Expansivity
• CPC Class Codes: F05D 2300/50212 dissimilar
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

A blade tip clearance system includes first and second control rings. The first control ring has a first coefficient of thermal expansion (CTE) and a first thermal response rate. The second control ring is located radially outward of and operatively connected to the first control ring and has a second CTE that is different from the first CTE and a second thermal response rate that is different from the first thermal response rate. Thermal expansion and contraction of the first and the second control rings controls a radial position of the blade tip clearance system relative to a rotating blade component.

Claims

1. A blade tip clearance system comprising:

a first control ring having a first coefficient of thermal expansion and a first thermal response rate;

a second control ring located radially outward of and operatively connected to the first control ring, the second control ring having a second coefficient of thermal expansion that is different from the first coefficient of thermal expansion and a second thermal response rate that is different from the first thermal response rate; and

wherein thermal expansion and contraction of the first and the second control rings are configured to control a radial position of the blade tip clearance system relative to a rotating blade component.

2. A blade tip clearance system as recited in claim 1, wherein the coefficient of thermal expansion of the first control ring is lower than that of the second control ring.

3. A blade tip clearance system as recited in claim 2, wherein the rate of thermal response of the first control ring is higher than that of the second control ring.

4. A blade tip clearance system as recited in claim 3, wherein the first control ring is a hollow structure including through holes to allow airflow therethrough.

5. A blade tip clearance system as recited in claim 4, wherein the first control ring includes interior fins to increase heat exchange therethrough.

6. A blade tip clearance system as recited in claim 3, wherein the second control ring is a full-hoop continuous ring.

7. A blade tip clearance system as recited in claim 1, further comprising seals forward and aft of the second control ring.

8. A blade tip clearance system as recited in claim 1, further comprising a carrier that radially centers the first and the second control rings.

9. A blade tip clearance system as recited in claim 8, further comprising flat feather seals at the walls of the carrier surrounding the second control ring to thermally isolate the second control ring.

10. A blade tip clearance system as recited in claim 8, wherein the second control ring is a segmented ring with a split at a circumferential location configured to minimize radial gaps between the outer control ring and the carrier.

11. A blade tip clearance system as recited in claim 8, wherein the carrier is a segmented structure with a forward and an aft section.

12. A blade tip clearance system as recited in claim 8, further comprising a support connected to the carrier to center the carrier relative to a case.

13. A blade tip clearance system as recited in claim 12, wherein the support comprises a support spline slot, the carrier comprises a carrier spline tab, and the support spline slot is slidably engaged to the carrier spline tab.

14. A blade tip clearance system as recited in claim 13, wherein the first control ring comprises a spline tab, and the support spline slot is slidably engaged to the spline tab of the first control ring.

15. A blade tip clearance system as recited in claim 13, wherein the second control ring comprises a spline tab, and the support spline slot is slidably engaged to the spline tab of the second control ring.

16. A blade tip clearance system as recited in claim 1, further comprising a blade outer air seal operatively connected to and radially inward of the first control ring that seals secondary flow air from the rotating blade component and forms an outer shroud for the rotating blade component.

17. A blade tip clearance system as recited in claim 1, further comprising at least one spring interposed between the first and the second control rings.

18. A gas turbine engine comprising:

a rotating structure including a plurality of rotating blades with radially outward tips;

a blade tip clearance system located adjacent to the radially outward tips comprising;

a carrier;

a blade outer air seal in communication with the carrier, the blade outer air seal including a radially inward seal face adjacent to the radially outward tips of the rotating blades;

an inner control ring configured to be radially centered with respect to the carrier, the inner control ring having a first coefficient of thermal expansion and a first thermal response rate;

an outer control ring configured to be radially centered with respect to the carrier, the outer control ring having a second coefficient of thermal expansion and a second thermal response rate; and

wherein thermal expansion and contraction of the inner and the outer control rings maintains a clearance between the radially inward seal face of the blade outer air seal and the radially outward tips of the rotating blades.

19. A gas turbine engine as recited in claim 18, wherein the carrier includes spline engagements slidably connected to a support.

20. A gas turbine engine as recited in claim 18, wherein the outer control ring is separated from the inner control ring by a portion of the carrier.