System for on-line assessment of the condition of thermal coating on a turbine vane

• US 20060132149A1
• Filed: 12/20/2004
• Published: 06/22/2006
• Est. Priority Date: 12/20/2004
• Status: Active Grant

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Siemens Westinghouse Power Corporation
• Inventors: Twerdochlib, Michael
• Granted Patent: US 7,123,031 B2
• Time in Patent Office: Days
• US Class Current: 324/693
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G01N 2203/0664 using witness specimens

Abstract

Aspects of the invention relate to a system for assessing the condition of a thermal barrier coating on a turbine vane during engine operation. According to embodiments of the invention, one or more wires can be passed along the airfoil portion of the vane. The wires can extend over, within, or beneath the thermal coating. An electrical current can be passed along the wires, and electrical resistance can be measured across the wires. Thus, if a portion of the thermal coating becomes damaged, then the wires located in that area may break. A disconnect in the wires can lead to an increase in resistance across the wires, which can alert an operator to a problem. Some assessment systems can provide a general indication of the magnitude of damage and whether the damage is spreading.

Claims

1. A system for monitoring the condition of a coating on a turbine engine component comprising:

a turbine engine component;

a coating applied over at least a portion of the turbine engine component;

at least one assessment wire extending about at least a portion of the component such that at least a portion of each assessment wire is in contact with the coating;

a power source electrically connected to the at least one assessment wire, wherein an electrical current is passed along the at least one assessment wire; and

a measuring device operatively associated with the at least one assessment wire so as to determine the electrical resistance across the assessment wire, whereby increases in resistance across the at least one assessment wire indicates a disconnect in the at least one assessment wire which further indicates possible damage to the coating.

2. The system of claim 1 wherein the turbine engine component is an airfoil.

3. The system of claim 1 wherein the coating is a thermal barrier coating.

4. The system of claim 1 wherein the at least one assessment wire is embedded within the coating.

5. The system of claim 1 wherein the at least one assessment wire includes a first group of assessment wires and a second group of assessment wires, and wherein the first group of wires and the second group of wires are angled relative to each other such that each wire from the first group of wires crosses at least one wire from the second group of wires.

6. The system of claim 1 further including a thermocouple provided in contact with at least the coating, wherein the thermocouple measures the temperature of at least the coating, whereby the temperature of the coating is used to discount changes in electrical resistance attributed to a change in temperature.

7. A system for monitoring the condition of a coating on an airfoil comprising:

an airfoil having a radially inner end and a radially outer end, the airfoil defining an outer peripheral surface;

a thermal coating substantially covering the outer peripheral surface of the airfoil;

a plurality of assessment wires extending about at least a portion of the airfoil, wherein at least a portion of each assessment wire is in contact with the thermal coating;

a power source electrically connected with the plurality of assessment wires, wherein an electrical current is passed along the plurality of assessment wires;

a measurement device operatively associated with the plurality of assessment wires so as to determine the electrical resistance across the assessment wires, whereby increases in resistance across the assessment wires can provide information as to the size and growth of possible damage to the thermal coating.

8. The system of claim 7 wherein the plurality of assessment wires are embedded in the thermal coating.

9. The system of claim 7 wherein the plurality of assessment wires are disposed beneath the thermal coating.

10. The system of claim 7 wherein the plurality of assessment wires are disposed over the thermal coating.

11. The system of claim 7 wherein at least some of the plurality of wires are electrically insulated from the rest of the plurality of wires.

12. The system of claim 7 wherein the plurality of wires are substantially equally spaced.

13. The system of claim 7 wherein the plurality of wires extend from near one radial end of the airfoil to near the opposite radial end of the airfoil.

14. The system of claim 7 wherein the plurality of wires extend substantially about the leading edge of the airfoil.

15. The system of claim 7 wherein the plurality of wires includes at least a first group of wires and a second group of wires, the first group of wires and the second group of wires are angled relative to each other such that each wire from the first group of wires crosses at least one wire from the second group of wires.

16. The system of claim 15 wherein the first and second groups of wires are electrically connected at at least some of the crossing points therebetween.

17. The system of claim 7 further including:

a first wire and a second wire operatively associated with the power source, wherein each of the plurality of assessment wires are electrically connected at one end to the first wire and at the other end to the second wire, wherein the first wire delivers the electrical current to each of the plurality of assessment wires and the second wire receives current from each of the assessment wires.

18. A method of on-line evaluation of the condition of a coating on a turbine engine component comprising:

providing a turbine engine having a component that is at least partially covered with a thermal coating, wherein at least one assessment wire extends about at least a portion of the component such that at least a portion of each assessment wire is in contact with the coating;

supplying an electrical current to the at least one assessment wire;

determining resistance across the at least one assessment wire; and

monitoring changes in resistance across the at least one assessment wire, whereby an increase in the resistance across the at least one assessment wire indicates a general assessment of the condition of the thermal coating.

19. The method of claim 18 wherein the supplying and measuring steps are performed during engine operation.

20. The method of claim 18 wherein the step of measuring is conducted on a substantially continuous basis.