Method of repairing a fuel nozzle

Abstract

A method of repairing a fuel nozzle is disclosed comprising the steps of forming a pilot assembly; installing into a repair bore; inserting a primary adaptor into a repair bore such that the primary adaptor is in flow communication with a pilot flow passage and the pilot assembly; and coupling the primary adaptor to a distributor and the new pilot assembly.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This Application claims priority to U.S. Provisional Application Ser. No. 61 / 044,116, filed Apr. 11, 2008, which is herein incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]This invention relates generally to fuel nozzles used in gas turbine engines, and more specifically to repairable fuel nozzles, components and methods of repairing fuel nozzle components and assemblies.[0003]Turbine engines typically include a plurality of fuel nozzles for supplying fuel to the combustor in the engine. The fuel is introduced at the front end of a burner in a highly atomized spray from a fuel nozzle. Compressed air flows around the fuel nozzle and mixes with the fuel to form a fuel-air mixture, which is ignited by the burner. Because of limited fuel pressure availability and a wide range of required fuel flow, many fuel injectors include pilot and main nozzles, with only the pilot nozzles being used during start-up, and both noz...

AI Technical Summary

Problems solved by technology

Because of limited fuel pressure availability and a wide range of required fuel flow, many fuel injectors include pilot and main nozzles, with only the pilot nozzles being used during start-up, and both nozzles being used during higher power operation.

Over time, continued exposure to high temperatures during turbine engine operations may induce thermal gradients and stresses in the conduits and fuel nozzle components which may damage the conduits or fuel nozzle components and may adversely affect the operation of the fuel nozzle.

For example, thermal gradients may cause fuel flow reductions in the conduits and may lead to excessive fuel maldistribution within the turbine engine.

Exposure of fuel flowing through the conduits and orifices in a fuel nozzle to high temperatures may lead to coking of the fuel and lead to blockages and non-uniform flow.

To provide low emissions, modern fuel nozzles require numerous, complicated internal air and fuel circuits to create multiple, separate flame zones.

Furthermore, over time, continued operation with damaged fuel nozzles may result in decreased turbine efficiency, turbine component distress, and / or reduced engine exhaust gas temperature margin.

Assembling and repairing such conventional fuel nozzles is time consuming, difficult and expensive.

Conventional gas turbine engine components such as, for example, fuel nozzles and their associated swirlers, conduits, distribution systems, venturis and mixing systems are generally expensive to fabricate and / or repair because the conventional fuel nozzle designs having complex swirlers, conduits and distribution circuits and venturis for transporting, distributing and mixing fuel with air include a complex assembly and joining of more than thirty components.

More specifically, the use of braze joints can increase the time needed to fabricate such components and can also complicate the fabrication process for any of several reasons, including: the need for an adequate region to allow for braze alloy placement; the need for minimizing unwanted braze alloy flow; the need for an acceptable inspection technique to verify braze quality; and, the necessity of having several braze alloys available in order to prevent the re-melting of previous braze joints.

Moreover, numerous braze joints may result in several braze runs, which may weaken the parent material of the component.

The presence of numerous braze joints can undesirably increase the weight and the cost of repairing, assembling and inspection of the components and assemblies.

Repair of a damaged conventional fuel nozzle is usually difficult, involving disassembly of the fuel nozzle assembly components to remove the damaged component.

However, such an approach is both expensive and results in reduced performance by introducing undesirable steps in the fuel wetted areas of nozzle component such as a venturi.

Other known manufacturing methods such as laser cladding often result in imperfections and inclusions in the formed or repaired part resulting from incomplete fusion of the melted layers to the underlying substrate or previously welded material.

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