Apparatus and related method for sensing cracks in rotating engine blades

• US 20090092491A1
• Filed: 10/05/2007
• Published: 04/09/2009
• Est. Priority Date: 10/05/2007
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Cairo, Ronald Ralph, Chen, Jianqiang
• Granted Patent: US 7,696,893 B2
• Time in Patent Office: Days
• US Class Current: 416/61
• CPC Class Codes: F04D 27/001 Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring
• CPC Class Codes: F04D 27/0292 Stop safety or alarm devices, e.g. stop-and-go control; Disposition of check-valves
• CPC Class Codes: F04D 29/322 Blade mountings
• CPC Class Codes: G01R 31/343 in operation

Abstract

A method and apparatus for detecting structural anomalies in the body of rotating members of an engine involves establishing an electric circuit in the body of the rotating members by embedding a network of electrically conductive fibers. Upon rotation of the members in the presence of a magnetic field, an electric current flows in the electrically conductive fibers of the rotating members. Detection of a structural anomaly in any of the rotating members results from detecting a break of the electric circuit.

Claims

1. A method for detecting cracks or structural breaks in the body of rotating compressor blades of an engine, comprising:

a) embedding electrically conductive carbon fibers in the body of said blades;

b) connecting in series the fibers embedded in all the said blades;

c) embedding at least one magnet at a position along the periphery of a casing enclosing said blades;

d) creating an electric circuit along the embedded network of carbon fibers;

e) detecting a break in said electric circuit caused by the occurrence of a crack or a structural break at a location in one of said blades.

2. The method according to claim 1, wherein said engine is any one of a gas turbine, steam turbine, or aircraft engine.

3. The method according to claim 1, wherein a) comprises impregnating the carbon fibers with a matrix material.

4. The method according to claim 3, wherein the matrix material comprises any one of epoxy or polymer.

5. The method according to claim 1, wherein a) comprises embedding the carbon fibers along the periphery of each rotating blade into a trough in the body of each blade.

6. The method according to claim 3, wherein the carbon fibers are bonded to the blades using non-conductive matrix and/or a non-conductive adhesive.

7. The method according to claim 3, wherein the fiber volume of the embedded carbon material is less than about 30%.

8. The method of claim 1, wherein c) comprises aligning the at least one magnet with the mid-chord of a blade.

9. The method of claim 1, wherein detection of a crack or a structural break results in the creation of a signal that provides an alarm to an operator.

10. An apparatus for detecting cracks or structural breaks formed in the body of rotating compressor blades of an engine, comprising:

a network of electrically conductive carbon fibers embedded in the body of said blades;

at least one magnet embedded at a position along the periphery of a casing enclosing said blades;

detection means for detecting a break in the electric circuit established when said blade rotates under the influence of a magnetic field from the magnet, said break in the electric circuit caused by a crack or a structural break at a location in one of said blades.

11. The apparatus according to claim 10, wherein said engine is any one of a turbine, steam turbine, or aircraft engine.

12. The apparatus according to claim 10, wherein the carbon fibers are impregnated with a matrix material.

13. The apparatus according to claim 12 wherein the matrix material comprises one of epoxy or polymer.

14. The apparatus according to claim 10, wherein the carbon fibers are embedded along the periphery of each rotating blade into a trough in the body of each blade.

15. The apparatus according to claim 12, wherein the carbon fibers are bonded to the blades using non-conductive matrix and/or a non-conductive adhesive.

16. The apparatus according to claim 12, wherein the fiber volume of the embedded carbon material is less than about 30%.

17. The apparatus according to claim 10, wherein the at least one magnet is aligned with the mid-chord of a blade.

18. The apparatus of claim 10, further comprising means for the generation of a signal that provides an alarm to an operator.

19. A method for detecting structural anomalies formed in the body of rotating members of an engine, comprising:

a) establishing a network of embedded electrically conductive fibers in said members;

b) positioning a magnetic member relative to the rotating members;

c) detecting a break in the electric circuit created along the embedded fibers due to the presence of the magnetic member, said break in the electric circuit being caused by the occurrence of a structural anomaly in the body of a rotating member;

d) generating warning signals upon detection of the break in the electric circuit.