Advanced military gas turbines are now being designed and developed with emphasis on high performance , low emissions, and low cost. In today's environment, high performance engines replacing current production must reduce emissions or not exceed current levels. Smoke has always been an issue with military engines, and needs to be kept at levels that cannot be observed. CO emissions also need to be reduced, especially at full power when the combustor operates close to stoichiometric, and high CO levels result in combustion inefficiency and possible heat release in the turbine. More recently, NOx emissions are a concern for military engines. This NOx emissions goal is extremely challenging since newer engines are run at higher pressure ratios (meaning higher P3 and T3), and the overall combustor fuel-air ratio continues to climb toward stoichiometric (resulting in T4 approaching stoichiometric).

CFDRC is developing an advanced fuel injector to meet these requirements designed specifically for JSF application. The fuel injector will not only provide high performance (including high combustion efficiency, low pattern factor, and high turndown fuel-air ratio), but also reduced emissions (including NOx, CO, UHC, and smoke). The fuel injector design will employ fuel thermal management features that provide for increased life of injector. The design is affordable due to its simplified design, and will also reduce the cost of the combustor lines (by eliminating the need for liner orifices).

This fuel injector is based on CFDRC's lean direct fuel injector (LDI) technology (U.S. Patent 6,272,840) which has demonstrated NOx reduction levels of 60-70% compared to 1996 ICAO standards for the Landing/Takeoff (LTO) cycle, as well as demonstrating a combustor lean blowout fuel-air ratio less than 0.005 at idle conditions.

A new version of the CFDRC fuel injector applicable to high performance miitary engines (i.e. JSF engine) has been demonstrated. For military engines, overall combustor fuel-air ratios at full power are closer to stoichiometric than commercial engines, and the concept of a completely lean injector/combustor is not feasible. In our concept, half of the fuel is burned at lean conditions, and half of the fuel is burned at rich conditions, both of which produce low NOx, at the full power condition. The only substantial NOx formed is where the rich pilot products mix and burn with the excess air from the mainstream.

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