Gas turbine engines, such as those used to power modern commercial aircraft, typically include a compressor for pressurizing a supply of air, a combustor for burning fuel in the presence of the pressurized air, and a turbine for extracting energy from the resultant combustion gases. The combustor typically includes radially spaced apart inner and outer liners. The inner and outer liners generally define an annular combustion chamber between the compressor and the turbine. A number of circumferentially distributed fuel injectors typically project into the forward end of the combustion chamber to supply the fuel to the combustion chamber, and one or more rows of circumferentially distributed air orifices in the liners admit air into the combustion chamber.
Modern combustors generally attempt to operate at very high temperatures, to achieve high operability, and to produce relatively low gaseous pollutant emissions during combustion, particularly oxides of nitrogen (NOx). One type of combustor that may provide one or more of these advantages is a rich burn, quick quench, lean burn (RQL) combustor, which includes the following three serially-arranged combustion zones: a rich burn zone at the forward end of the combustor, a quench or dilution zone downstream of the rich burn zone, and a lean burn zone downstream of the quench zone. By precisely controlling the stoichiometries between the air and fuel in each zone, high-temperature excursions can be reduced and the resulting NOx emissions can be minimized. The high temperature and operability requirements, however, often require particular consideration for cooling the combustion liners. Some cooling schemes may present aerodynamic and mechanical design challenges, particularly in the quench zone of the combustor in which the fuel-rich gases from the rich burn zone are rapidly mixed with excess air and passed to the lean burn zone. The design and development of the quench zone geometry is commonly one of the primary challenges in the successful implementation of low-emissions RQL combustors.
Accordingly, it is desirable to provide RQL combustors with a geometry that promotes low NOx emissions and operability is increased. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.