Mixer assembly for combustor of a gas turbine engine having a main mixer with improved fuel penetration

Abstract

A mixer assembly for use in a combustion chamber of a gas turbine engine includes a pilot mixer, a main mixer, and a fuel manifold positioned between the pilot mixer and main mixer. The pilot mixer includes an annular pilot housing having a hollow interior and a pilot fuel nozzle mounted in the housing and adapted for dispensing droplets of fuel to the hollow interior of the pilot housing. The main mixer includes: a main housing surrounding the pilot housing and defining an annular cavity having an upstream end and a downstream end including an upstream wall, an outer wall and an inner wall; a plurality of fuel injection ports for introducing fuel into the cavity, with the fuel injection ports being circumferentially spaced at a designated axial location of the inner wall of the annular cavity; and a swirler arrangement including at least one swirler in flow communication with the annular cavity, the swirler being incorporated into the outer wall of the annular cavity and extending from an upstream end to a downstream end, wherein each swirler of the arrangement has a plurality of vanes for swirling air traveling through such swirler to mix air and the droplets of fuel dispensed by the fuel injection ports. The main housing further includes a first plurality of passages oriented to provide air jets in a substantially axial direction into the annular cavity and a second plurality of passages oriented to provide air jets in a substantially radial direction into the annular cavity

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a staged combustion system in which the production of undesirable combustion product components is minimized over the engine operating regime and, more particularly, to a fuel injection arrangement for the main mixer of such system which enhances fuel penetration into an annular cavity for improved mixing of fuel and air therein. [0002] Air pollution concerns worldwide have led to stricter emissions standards both domestically and internationally. Aircraft are governed by both Environmental Protection Agency (EPA) and International Civil Aviation Organization (ICAO) standards. These standards regulate the emission of oxides of nitrogen (NOx), unburned hydrocarbons (HC), and carbon monoxide (CO) from aircraft in the vicinity of airports, where they contribute to urban photochemical smog problems. Such standards are driving the design of gas turbine engine combustors, which also must be able to accommodate the desire ...

AI Technical Summary

Problems solved by technology

Balancing the operation of a combustor 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, as well as lower power output and lower thermal efficiency.

It has been found that fuel injected into such annular cavity has a tendency to break apart more quickly than desired and / or reside too closely to the inner radial surface thereof.

In either event, the ability of the fuel and air in the annular cavity to form a more uniform mixture is impeded.

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