Fuel distribution within a gas turbine engine combustor
A fuel system for a gas turbine engine includes a plurality of duplex nozzles arranged on each side of top dead center and a plurality of simplex nozzles. A primary manifold is operable to communicate fuel to a primary flow jet in each of the plurality of duplex nozzles and a secondary manifold is operable to communicate fuel to a secondary flow jet in each of the plurality of duplex nozzles and a secondary flow jet in each of the plurality of simplex nozzles. An equalizer valve that is in communication with both the primary manifold and the secondary manifold distributes fuel at various pressures to both the primary and secondary manifolds.
1. A method of noise control from a combustor of a gas turbine engine comprising:
forming a plurality of alternating local circumferential zones about an engine longitudinal axis with different fuel-air ratios within the combustor including forming a high fuel-air ratio circumferential zone at a top center position and forming a low fuel-air ratio circumferential zone at a bottom center position relative to the engine longitudinal axis, wherein a high fuel-air ratio is generated by at least two duplex fuel nozzles disposed on either side of the top center position and a low fuel-air ratio is generated by at least two simplex fuel nozzles disposed on either side of a bottom center position.
2. The method as recited in claim 1 , further comprising:
alternating the plurality of alternating local circumferential zones with varied fuel-air ratios.
3. The method as recited in claim 2 , further comprising:
forming the plurality of alternating local circumferential zones as high-low-high-low local fuel-air ratios.
4. The method as recited in claim 1 , further comprising:
locating at least one of a plurality of duplex nozzles adjacent to a fuel igniter to form at least one high local fuel-air ratio within at least one of the plurality of alternating local circumferential zones.
5. The method as recited in claim 4 , further comprising:
locating at least one of the plurality of duplex nozzles opposite the fuel igniter to form at least one high local fuel-air ratio within at least one of the plurality of alternating local circumferential zones.
6. A method of noise control from a combustor of a gas turbine engine comprising:
selectively forming a plurality of local circumferential zones with different fuel-air ratios within the combustor including forming a high fuel-air ratio circumferential zone at a top dead center position and forming a low fuel-air ratio circumferential zone at a bottom dead center position; and
alternating a plurality of duplex nozzles and a plurality of simplex nozzles to define the plurality of local circumferential zones wherein the plurality of duplex nozzles includes ten (10) duplex nozzles and the plurality of simplex nozzles includes six (6) simplex nozzles.
7. The method as recited in claim 6 , further comprising:
selectively equalizing a fuel pressure between a primary manifold and a secondary manifold, the primary manifold in communication with a primary flow jet in each of the plurality of duplex nozzles and the secondary manifold in communication with a secondary flow jet in each of the plurality of duplex nozzles and a secondary flow jet in each of the plurality of simplex nozzles.
8. The method as recited in claim 7 , further comprising:
selectively opening a valve between the primary manifold and the secondary manifold.
9. The method as recited in claim 7 , further comprising:
equalizing the fuel pressure in response to a power condition greater than a lowest power condition.
10. The method as recited in claim 6 , further comprising:
selectively dividing a fuel pressure between a primary manifold and a secondary manifold, the primary manifold in communication with a primary flow jet in each of the plurality of duplex nozzles and the secondary manifold in communication with a secondary flow jet in each of the plurality of duplex nozzles and a secondary flow jet in each of the plurality of simplex nozzles.
11. The method as recited in claim 10 , further comprising:
selectively dividing the fuel pressure in response to a low power condition.
12. The method as recited in claim 10 , further comprising:
selectively forming the plurality of local circumferential zones with varied fuel-air ratios within the combustor in response to a low power condition.
13. A method of noise control from a combustor of a gas turbine engine comprising:
selectively forming a plurality of local circumferential zones with different fuel-air ratios within the combustor including forming a high fuel-air ratio circumferential zone at a top dead center position and forming a low fuel-air ratio circumferential zone at a bottom dead center position; and
alternating a plurality of duplex nozzles and a plurality of simplex nozzles to define the plurality of local circumferential zones wherein the plurality of duplex nozzles includes ten (10) duplex nozzles and the plurality of simplex nozzles includes six (6) simplex nozzles;
selectively dividing a fuel pressure between a primary manifold and a secondary manifold in response to a low power condition, the primary manifold in communication with a primary flow jet in each of the plurality of duplex nozzles and the secondary manifold in communication with a secondary flow jet in each of the plurality of duplex nozzles and a secondary flow jet in each of the plurality of simplex nozzles, wherein the low power condition comprises power required for approach conditions, wherein the power required for approach conditions is greater than power at a cruise condition.