SYSTEMS AND METHODS FOR RESIZING HOLES

The present application thus provides a method of filling an existing hole in a surface of a turbine component. The method may include the steps of enlarging the existing hole, placing a rivet into the enlarged hole, welding the rivet into place, and grinding the rivet to be flush with the surface of the turbine component.

TECHNICAL FIELD

The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to systems and methods for resizing existing holes such as premix fuel inlet holes within a vane turbine fuel nozzle assembly in a fast, efficient, and safe manner.

BACKGROUND OF THE INVENTION

In gas turbine engines, a combustor includes a number of fuel nozzles. The fuel nozzles typically include a subassembly of generally concentric tubes defining a central passage for supplying diffusion fuel gas and a pair of concentric passages for supplying premix fuel gas. Spaced from and surrounding the subassembly may be an inlet flow conditioner for directing and confining a flow of inlet air past a number of circumferentially spaced vanes carried by the subassembly. The vanes may be in communication with the concentric fuel gas supply passages. Particularly, the vanes may include outer and inner premix fuel supply holes for supplying gas from the respective passages for mixing with the flow of inlet air. The air-fuel gas mixture may be swirled by the vanes downstream of the premix fuel supply holes for subsequent combustion in a combustion chamber.

The fuel supply holes may be sized to achieve a predetermined pressure drop for a specific fuel energy content and may have a specific radial/axial pattern that achieves a radial fuel-to-air ratio that is favorable for overall combustor performance. If the energy content of the fuel increases, the hole sizes may need to be decreased. If it is desired to change the hole pattern on a nozzle, the hole positions also may change. To decrease the fuel hole size or change the overall hole pattern, the holes may be machined open and a cylinder of metal may be brazed into place before the new holes are installed. For repeatability, the cylinder outside diameter should be large enough to leave a sufficient segment of the cylinder perimeter after the new hole is installed when taking into account the original and final hole positions in addition to the cylinder outside diameter tolerances. The replacement piece, however, may be expensive and the overall process may produce excessive amounts of scrap as well as unneeded or outdated inventory.

SUMMARY OF THE INVENTION

The present application and the resultant patent thus provide a method of filling an existing hole in a surface of a turbine component. The method may include the steps of enlarging the existing hole, placing a rivet into the enlarged hole, welding the rivet into place, and grinding the rivet to be flush with the surface of the turbine component.

The present application and the resultant patent further provide a method of replacing an existing fuel supply hole in a vane of a fuel nozzle assembly. The method may include the steps of enlarging the existing hole, placing a rivet into the enlarged hole, fusion welding the rivet into place, grinding the rivet to be flush with the vane, and machining a new fuel supply hole in the vane. The new fuel supply hole is smaller than the existing fuel supply hole.

DETAILED DESCRIPTION

Referring now to the drawings, in which like numerals refer to like elements throughout the several views,FIG. 1shows a schematic diagram of gas turbine engine10as may be used herein. The gas turbine engine10may include a compressor15. The compressor15compresses an incoming flow of air20. The compressor15delivers the compressed flow of air20to a combustor25. The combustor25mixes the compressed flow of air20with a pressurized flow of fuel30and ignites the mixture to create a flow of hot combustion gases35. Although only a single combustor25is shown, the gas turbine engine10may include any number of combustors25. The flow of hot combustion gases35is in turn delivered to a turbine40. The flow of hot combustion gases35drives the turbine40so as to produce mechanical work. The mechanical work produced in the turbine40drives the compressor15via a shaft45and an external load50such as an electrical generator and the like.

The gas turbine engine10may use natural gas, various types of syngas, liquid fuels, and/or other types of fuels and blends thereof. The gas turbine engine10may be any one of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y., including, but not limited to, those such as a7or a9series heavy duty gas turbine engine and the like. The gas turbine engine10may have different configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also may be used herein together.

FIGS. 2-4represent an example of a conventional fuel nozzle assembly55that may be used with the gas turbine engine10. Generally, the fuel nozzle assembly55may include a subassembly60and a surrounding air inlet conditioner62. The subassembly60may include a central tube64and a pair of concentric tubes66and68defining therebetween discrete annular fuel passages70and72. The central tube64supplies diffusion gas to a combustion zone (not shown) located downstream of the fuel nozzle assembly55. The subassembly60further includes a number of vanes74that are shown inFIG. 2as circumferentially spaced from each other around the outer tube68. The vanes74may include outer premix fuel supply holes76supplied with gaseous fuel from the passage72and a number of inner premix fuel supply holes78supplied with gaseous fuel from the passage70. Each vane74may have a pair of outer and inner plenums80and82, respectively, confined between opposite side walls84and86of the vane74. The holes76and78may be fluidically connected with the passages72and70through the outer and inner plenums80and82, respectively.

The outer premix fuel supply holes76may include a pair of the radially spaced premix fuel supply holes76through one wall84of the vane74and a single premix fuel supply hole76through the opposite side wall86of the vane74. Downstream portions88of the vanes74may impart a swirl to the flow of premixed air and gaseous fuel flowing between the subassembly60and the inlet flow conditioner62, the gaseous fuel being supplied to the air stream via the outer and inner premix fuel supply holes76and78, respectively.

FIGS. 5-12show exemplary systems and method steps in resizing a hole100such as the fuel supply holes76in a turbine component110such as a vane115of a fuel nozzle assembly120. Other types of surfaces125also may be used herein. AtFIG. 5and step130, the existing holes76may be enlarged by plunge electrical discharge machining (EDM), a drill or ream process, and similar techniques. At step140, replacement rivets150may be fabricated. As is shown inFIG. 6, the rivets150may have a body160, a flange170, and an upper cap180. The size and shape of the rivets150may vary. The rivets150may be made from the same or similar high temperature material alloys as the components of the fuel nozzle assembly120. AtFIGS. 7 and 8and step190, the rivets150may be pressed into the enlarged holes185until the rivets150are largely flush with the surface125of the vane115. AtFIG. 9and step200, the rivets150may be fusion welded into place within the enlarged hole185. Other types of joining techniques may be used herein. AtFIG. 10and step210, the cap180of the rivet150may be ground down to be flush with the surface125of the vane115. Other types of finishing techniques may be used herein.

AtFIG. 11and step220, the new holes100may be machined in the vane115. The size, number, and location of the holes100may be varied from the original configuration. Specifically, any number of the holes110may be created in any suitable size, shape, or configuration. The holes100may be created via a plunge EDM process as above or via similar machining techniques. Other components and other configurations may be used herein.

The resizing steps described herein thus allows an upgraded configuration to the vanes115of the fuel nozzle assembly120or other type of turbine component110. Moreover, unwanted fuel nozzle inventory may be retrofitted with vanes115having useful hole sizes and configurations and returned to service. The resultant fuel nozzle assembly120thus may have comparable or even improved dynamics, flame holding, emissions, and the like. As opposed to the known expensive brazed cylindrical plugs and aluminide closure methods, the use of the custom rivets150provides consistent hole to hole flow repeatability.