Three-piece airblast fuel injector
A fuel system includes an external cool air source, and a fuel injector. The fuel injector includes a fuel circuit, an outer air circuit, an inner air circuit, and an outlet. The fuel circuit receives liquid fuel from a fuel inlet. The outer air circuit receives cool air from the cool air source and substantially surrounds the fuel circuit. The inner air circuit is in fluid communication with the outer air circuit and a portion of the fuel circuit substantially surrounds the inner air circuit. The outlet provides atomized fuel from the fuel circuit, outer air circuit and inner air circuit to a combustor.
1. A fuel system comprising:
an external cool air source; and
a fuel injector that comprises:
a fuel circuit that receives liquid fuel from a fuel inlet and provides the liquid fuel to a prefilmer;
an outer air circuit that receives cool air from the cool air source, wherein the outer air circuit substantially surrounds the fuel circuit;
an inner air circuit in fluid communication with the outer air circuit, wherein the inner air circuit receives a portion of the cool air from the outer air circuit, and wherein all the liquid fuel passes to the prefilmer through a portion of the fuel circuit that substantially surrounds the inner air circuit; and
an outlet that provides atomized fuel from the fuel circuit, outer air circuit and inner air circuit to a combustor.
2. The fuel system of claim 1 , wherein the fuel injector further comprises:
a body piece-part;
an air-swirler piece-part; and
a housing piece-part; and
wherein the fuel circuit comprises:
a fuel passageway in the body piece-part that is in fluid communication with the fuel inlet; and
a fuel chamber defined between an outer surface of the body piece-part and an inner surface of the air-swirler piece-part, wherein the fuel chamber is in fluid communication with the fuel passageway; and
wherein the prefilmer is in fluid communication with the fuel chamber, wherein the prefilmer is in fluid communication with the outlet.
3. The fuel system of claim 2 , wherein the outer air circuit comprises:
a first air chamber defined by an inner surface of the housing piece-part and an outer surface of the body, wherein the first air chamber is in fluid communication with the air inlet; and
a second air chamber defined by the inner surface of the housing piece-part and an outer surface of the air-swirler, wherein the second air chamber is in fluid communication with the first air chamber and the outlet.
4. The fuel system of claim 3 , wherein the inner air circuit comprises:
an inner air passage within the body that is in fluid communication with the prefilmer, and wherein the inner air passage is in fluid communication with the first air chamber.
5. The fuel system of claim 4 , wherein the inner air passage and the second air chamber provide the cool air to the prefilmer to atomize the liquid fuel.
6. The fuel system of claim 3 , wherein a plurality of vanes are included on the outer surface of the air-swirler piece-part to swirl the cool air from the first air chamber into the second air chamber.
7. A method of shielding liquid fuel in a fuel injector, the method comprising:
receiving the liquid fuel at a fuel inlet of the fuel injector, wherein the fuel injector includes a fuel circuit;
receiving cool air at an air inlet of the fuel injector from an external cool air source, wherein the fuel injector includes an inner air circuit and an outer air circuit, and wherein the outer air circuit substantially surrounds the fuel circuit, and wherein a portion of the fuel circuit substantially surrounds the inner air circuit;
providing all the liquid fuel to a prefilmer through the portion of the fuel circuit that substantially surrounds the inner air circuit;
providing, by the outer air circuit, a portion of the cool air to the inner air circuit;
atomizing the liquid fuel with the cool air in the inner and outer air circuits; and
providing the atomized fuel to a combustor.
8. The method of claim 7 , wherein the fuel injector further comprises:
a body piece-part;
an air-swirler piece-part; and
a housing piece-part; and
wherein the fuel circuit comprises:
a fuel passageway in the body piece-part that is in fluid communication with the fuel inlet;
a fuel chamber defined between an outer surface of the body piece-part and an inner surface of the air-swirler piece-part, wherein the fuel chamber is in fluid communication with the fuel passageway; and
wherein the prefilmer is in fluid communication with the fuel chamber, wherein the prefilmer is in fluid communication with the outlet.
9. The method of claim 8 , wherein the outer air circuit comprises:
a first air chamber defined by an inner surface of the housing piece-part and an outer surface of the body, wherein the first air chamber is in fluid communication with the air inlet; and
a second air chamber defined by the inner surface of the housing piece-part and an outer surface of the air-swirler, wherein the second air chamber is in fluid communication with the first air chamber and the outlet; and
wherein receiving cool air at an air inlet further comprises providing the cool air to the first air chamber.
10. The method of claim 9 , wherein the inner air circuit comprises:
an inner air passage within the body that is in fluid communication with the prefilmer, and wherein the inner air passage is in fluid communication with the first air chamber; and
wherein atomizing the liquid fuel comprises providing cool air from the inner air passage to the prefilmer.
11. The method of claim 10 , wherein atomizing the liquid fuel further comprises providing air from the second air chamber to the prefilmer.
12. The method claim 9 , further comprising swirling the air from the first air chamber to the second air chamber using a plurality of vanes on an outer surface of the air-swirler piece-part.
13. A fuel system comprising:
an external cool air source; and
a fuel injector that comprises:
a body piece-part;
an air-swirler piece-part;
a housing piece-part;
a fuel circuit that receives liquid fuel from a fuel inlet, wherein the fuel circuit comprises:
a fuel passageway in the body piece-part that is in fluid communication with the fuel inlet;
a fuel chamber defined between an outer surface of the body piece-part and an inner surface of the air-swirler piece-part, wherein the fuel chamber is in fluid communication with the fuel passageway; and
a prefilmer in fluid communication with the fuel chamber, wherein the prefilmer is in fluid communication with an outlet;
an outer air circuit that receives cool air from the cool air source, wherein the outer air circuit substantially surrounds the fuel circuit, and wherein the outer air circuit comprises:
a first air chamber defined by an inner surface of the housing piece-part and an outer surface of the body, wherein the first air chamber is in fluid communication with the air inlet; and
a second air chamber defined by the inner surface of the housing piece-part and an outer surface of the air-swirler, wherein the second air chamber is in fluid communication with the first air chamber and the outlet; and
an inner air circuit in fluid communication with the outer air circuit, wherein a portion of the fuel circuit substantially surrounds the inner air circuit, wherein the inner air circuit comprises an inner air passage within the body that is in fluid communication with the prefilmer, and wherein the inner air passage is in fluid communication with the first air chamber;
wherein the outlet provides atomized fuel from the fuel circuit, outer air circuit and inner air circuit to a combustor.
14. The fuel system of claim 13 , wherein the inner air passage and the second air chamber provide the cool air to the prefilmer to atomize the liquid fuel.
15. The fuel system of claim 13 , wherein a plurality of vanes are included on the outer surface of the air-swirler piece-part to swirl the cool air from the first air chamber into the second air chamber.