ESTABLISHING A THROAT AREA OF A GAS TURBINE NOZZLE, AND A TECHNIQUE FOR MODIFYING THE NOZZLE VANES

• US 20030177640A1
• Filed: 03/21/2002
• Published: 09/25/2003
• Est. Priority Date: 03/21/2002
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Messelling, William G., Marques, Marcio Lins Tinoco, de Rezende, Tathiana Carneiro, von Montfort, Andreas Martin, Budinger, David Edwin
• Granted Patent: US 6,789,315 B2
• Time in Patent Office: Days
• US Class Current: 29/889.1
• CPC Class Codes: B23P 6/002 Repairing turbine components, e.g. moving or stationary blades, rotors, B23P6/045 takes precedence
• CPC Class Codes: F01D 5/005 Repairing methods or devices
• CPC Class Codes: F01D 5/147 Construction, i.e. structural features, e.g. of weight-saving hollow blades F01D5/148, F01D5/16 and F01D5/20 take precedence; blade shape F01D5/141; blades with cooling or heating channels or cavities F01D5/18; heating, heat-insulating or cooling means on blades F01D5/18
• CPC Class Codes: F01D 9/02 Nozzles; Nozzle boxes; Stator blades; Guide conduits , e.g. individual nozzles nozzle boxes F01D9/047
• CPC Class Codes: F05D 2230/23 by permanently joining parts together
• CPC Class Codes: F05D 2240/80 Platforms for stationary or moving blades
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 29/49318 Repairing or disassembling
• CPC Class Codes: Y10T 29/49323 Assembling fluid flow directing devices, e.g., stators, diaphragms, nozzles
• CPC Class Codes: Y10T 29/49771 Quantitative measuring or gauging
• CPC Class Codes: Y10T 29/49778 with aligning, guiding, or instruction

Abstract

A final throat area of a gas turbine nozzle circumferential structure is established by providing at least two gas turbine nozzle vanes, and determining a pairwise initial throat area between each pair of gas turbine nozzle vanes. For each pair of gas turbine nozzle vanes whose pairwise initial throat area is not within the final pairwise throat area target range, a trailing edge of at least one of the gas turbine nozzle vanes is extended responsive to the step of determining the initial pairwise throat area, so that a final pairwise throat area is within a final pairwise throat area target range. A nozzle plurality of pairs of gas turbine nozzle vanes that together comprise the gas turbine nozzle circumferential structure may be selected so that a sum of their final pairwise throat areas is within a final total throat area target range. The trailing edge may be extended for this or other purposes by affixing an extension wire to the trailing edge extending lengthwise along the trailing -edge, applying a braze material to the extension wire and the trailing edge, and heating the braze material to a brazing temperature to melt at least a portion of the braze material and, upon cooling, to bond the extension wire and the braze material to the trailing edge.

Claims

1. A method for extending a rounded trailing edge of a gas turbine nozzle vane, comprising the steps of

providing a gas turbine nozzle vane having the rounded trailing edge extending lengthwise between a root and a tip of the gas turbine nozzle vane;

affixing an extension wire to the trailing edge extending lengthwise along the trailing edge;

applying a braze material to the extension wire and the trailing edge; and

heating the braze material to a brazing temperature to melt at least a portion of the braze material and, upon cooling, to bond the extension wire and the braze material to the trailing edge.

2. The method of claim 1, wherein the gas turbine nozzle vane is made of a nozzle-vane nickel-base superalloy, and the extension wire is made of an extension-wire nickel-base superalloy.

3. The method of claim 2, wherein the extension-wire nickel-base superalloy has a nominal composition in weight percent of about 12.0 percent cobalt, about 6.8 percent chromium, about 1.5 percent molybdenum, about 4.9 percent tungsten, about 2.8 percent rhenium, about 6.35 percent tantalum, about 6.15 percent aluminum, about 1.5 percent hafnium, about 0.12 percent carbon, about 0.015 percent boron, balance nickel and minor elements.

4. The method of claim 1, wherein the step of applying the braze material includes the step of

applying a first layer of a high-melt filler alloy into a gap region between the extension wire and the trailing edge, and thereafter

applying a second layer of a braze composition overlying the first layer.

5. The method of claim 4, wherein the first layer is a first-layer nickel-base superalloy having a first-layer-nickel-base-superalloy melting point greater than the brazing temperature.

6. The method of claim 5, wherein the first-layer nickel-base superalloy is selected from the group consisting of

a first nickel-base superalloy having a nominal composition, in weight percent, of about 7.5 percent cobalt, about 9.75 percent chromium, about 1.5 percent molybdenum, about 6.0 percent tungsten, about 4.8 percent tantalum, about 4.2 percent aluminum, about 3.45 percent titanium, about 0.15 percent hafnium, about 0.05 percent carbon, about 0.004 percent boron, about 0.5 percent niobium, balance nickel and minor elements, and

a second nickel-base superalloy, having a nominal composition in weight percent of about 12.0 percent cobalt, about 6.8 percent chromium, about 1.5 percent molybdenum, about 4.9 percent tungsten, about 2.8 percent rhenium, about 6.35 percent tantalum, about 6.15 percent aluminum, about 1.5 percent hafnium, about 0.12 percent carbon, about 0.015 percent boron, balance nickel and minor elements.

7. The method of claim 4, wherein the second layer is a second-layer nickel-base superalloy having a second-layer-nickel-base-superalloy melting point less than the brazing temperature.

8. The method of claim 7, wherein the second-layer nickel-base superalloy is a mixture of a first component having a first-component melting point greater than the brazing temperature and a second component having a second-component melting point less than the brazing temperature.

9. The method of claim 7, wherein the second-layer nickel-base superalloy is a mixture of

a first nickel-base superalloy, having a nominal composition in weight percent of about 12.0 percent cobalt, about 6.8 percent chromium, about 1.5 percent molybdenum, about 4.9 percent tungsten, about 2.8 percent rhenium, about 6.35 percent tantalum, about 6.15 percent aluminum, about 1.5 percent hafnium, about 0.12 percent carbon, about 0.015 percent boron, balance nickel and minor elements, and

a second nickel-base superalloy modified by the addition of silicon and boron and having a nominal composition, in weight percent, of about 0.16 percent carbon, about 4.5 percent silicon, about 14.0 percent chromium, about 9.5 percent cobalt, about 4.9 percent titanium, about 4.0 percent molybdenum, about 4.0 percent tungsten, about 3.0 percent aluminum, about 0.65 percent boron, about 0.03 percent zirconium, balance nickel and minor elements.

10. The method of claim 1, wherein the brazing temperature is from about 2190°

F. to about 2240°

F.

11. A method for establishing a final throat area of a gas turbine nozzle circumferential structure, comprising the steps of

providing a final pairwise throat area target range;

providing at least two gas turbine nozzle vanes;

thereafter

determining a pairwise initial throat area between each pair of gas turbine nozzle vanes; and

thereafter, for each pair of gas turbine nozzle vanes whose pairwise initial throat area is not within the final pairwise throat area target range, of

extending a trailing edge of at least one of the gas turbine nozzle vanes responsive to the step of determining the initial pairwise throat area, so that the final pairwise throat area is within the final pairwise throat area target range.

12. The method of claim 11, wherein the step of providing includes the step of

providing a nozzle plurality of pairs of gas turbine nozzle vanes together comprising the gas turbine nozzle circumferential structure.

13. The method of claim 11, including an additional step, of

providing a final total throat area target range, and

selecting a nozzle plurality of pairs of gas turbine nozzle vanes that together comprise the gas turbine nozzle circumferential structure, wherein a sum of their final pairwise throat areas is within the final total throat area target range.

14. The method of claim 11, wherein the step of extending includes the steps of

providing one of the gas turbine nozzle vanes having a rounded trailing edge extending lengthwise between a root and a tip of the gas turbine nozzle vane,

affixing an extension wire to the trailing edge extending lengthwise along the trailing edge,

applying a braze material overlying the extension wire and the trailing edge, and

brazing the braze material to the extension wire and to the trailing edge.