Method of manufacturing a unitary venturi

Abstract

A method for fabricating a unitary venturi is disclosed, the method comprising the steps of determining three-dimensional information of the unitary venturi having an annular venturi wall and a swirler having a plurality of vanes arranged circumferentially around a swirler axis, converting the three-dimensional information into a plurality of slices that each define a cross-sectional layer of the unitary venturi, and successively forming each layer of the unitary venturi by fusing a metallic powder using laser energy. Exemplary embodiments are disclosed, showing a unitary venturi comprising an annular venturi wall having a swirler axis and a heat shield located at an end wherein unitary venturi is made by using a rapid manufacturing process. In one aspect of the invention, the rapid manufacturing process is a laser sintering process.

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 venturis, and more specifically to unitary venturis having swirlers for promoting mixing of fuel and air and a heat shield for protection from combustion heat in fuel nozzles used in gas turbine engines.[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 bei...

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.

For example, one way in which the problem of minimizing the emission of undesirable gas turbine engine combustion products has been attacked is the provision of staged combustion.

It will be appreciated that balancing the operation of the first and second stage burners to allow efficient thermal operation of the engine, while simultaneously minimizing the production of undesirable combustion products, is difficult to achieve.

In that regard, operating at low combustion temperatures to lower the emissions of NOx, can also result in incomplete or partially incomplete combustion, which can lead to the production of excessive amounts of HC and CO, in addition to producing lower power output and lower thermal efficiency.

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

For example, thermal stresses 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.

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