| CFD Research Corporation (CFDRC)
has developed a lean direct fuel injector for application to all sizes of
aero gas turbine engines.The patented injector design (U.S.
Patent 6,272,840 B1) utilizes a bifurcated flow pattern structure
that produces low NOx emissions at full power conditions and low CO, UHC
and smoke emissions at low power. The design consists of three swirlers
and two fuel circuits, and a flow splitter that divides the airflow into
two airstreams. Two concentric fuel circuits fuel the two airstreams, producing
two distinct flames: a pilot flame and a main flame. This unique flame structure
allows separate control of two flame regions, but still allows them to interact.
A large percent of combustor airflow enters through the injector.
At low power (idle and approach), only the pilot circuit is fueled. The
pilot fuel flows into the pilot airstream, and a flame is anchored in
the bifurcated recirculation zone. Lean blowouts at idle conditions as
low as an injector equivalence ratio of 0.04 have been realized. Low CO,
UHC and smoke emissions have been demonstrated at these conditions. For
power settings above approach, the fuel flow through the pilot is reduced,
and the main is fueled. At cruise to max power conditions, only 10% of
the fuel goes through the pilot and 90% goes through the main to achieve
both low NOx and good stability. At max power conditions, the injector
equivalence ratio is approximately 0.60-0.65, and the flame is blue and
non-luminous, resulting in reduced heat loads to the liner. NOx emission
levels have been measured in single-injector tests that show this injector
has the potential to reduce the Landing/Takeoff (LTO) NOx levels by 60-70%
compared with 1996 ICAO standards.
CFDRC has the necessary expertise to adapt and further develop this fuel
injector for specific applications. In addition, a dual-fuel (gaseous
and liquid) design can be developed for industrial gas turbines. Click
here for other fuel injector applications at CFDRC.
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Contrast of Combustor Flow Patterns; a) Bifurcated
and b) Central Recirculation
Cross-Section of Patented CFDRC LE Fuel Injector
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