Fuel injection device
A main fuel injector of a fuel injection device includes: a main outer air passage including an inlet that is open outward in a radial direction, the main outer air passage taking in compressed air through the inlet; a main inner air passage including an inlet that is open inward in the radial direction, the main inner air passage taking in the compressed air through the inlet; a merged air passage, in which the compressed air taken in by the main outer air passage and the compressed air taken in by the main inner air passage merge together; and a main fuel injection port configured to inject a fuel into the compressed air taken in by the main outer air passage or into the compressed air taken in by the main inner air passage.
1. A fuel injection device that is supplied with compressed air from a forward side in an axial direction, which is a direction of an axis of the fuel injection device, the fuel injection device comprising:
a pilot fuel injector positioned on the axis of the fuel injection device; and
a main fuel injector disposed such that the main fuel injector encircles the pilot fuel injector, wherein
the main fuel injector includes:
a main outer air passage including an inlet that is open outward in a radial direction, the main outer air passage taking in the compressed air through the inlet;
a main inner air passage including an inlet that is open inward in the radial direction, the main inner air passage taking in the compressed air through the inlet;
a merged air passage, in which the compressed air taken in by the main outer air passage and the compressed air taken in by the main inner air passage merge together; and
a main fuel injection port configured to inject a fuel into the compressed air taken in by the main outer air passage or into the compressed air taken in by the main inner air passage,
wherein the inlet of the main outer air passage and the inlet of the main inner air passage are annular openings,
the merged air passage includes a boundary wall that is positioned at a forward part of the merged air passage in the axial direction, and
the boundary wall includes:
an outward deflector configured with a curved surface to deflect the compressed air taken in by the main outer air passage toward a rearward axial direction, such that a velocity component of the compressed air in a rearward axial direction increases; and
an inward deflector configured with a curved surface to deflect the compressed air taken in by the main inner air passage toward a rearward axial direction, such that a velocity component of the compressed air in the rearward axial direction increases.
2. The fuel injection device according to claim 1 , wherein
the main fuel injector further includes:
a main outer swirler provided at the inlet of the main outer air passage and configured to lead, inward in the radial direction, the compressed air taken in through the inlet of the main outer air passage and cause the compressed air to swirl around the axis of the fuel injection device; and
a main inner swirler provided at the inlet of the main inner air passage and configured to lead, outward in the radial direction, the compressed air taken in through the inlet of the main inner air passage and cause the compressed air to swirl around the axis of the fuel injection device.
3. The fuel injection device according to claim 1 , wherein
the main fuel injection port includes an outlet positioned upstream of an axial-direction rear end portion that is a boundary portion of the boundary wall between the outward deflector and the inward deflector.
4. The fuel injection device according to claim 3 , wherein
the main fuel injector includes:
a merging outer circumferential surface that demarcates the merged air passage and that is positioned rearward of the main outer air passage in the axial direction adjacently to the main outer air passage; and
a merging inner circumferential surface that demarcates the merged air passage and that is positioned rearward of the main inner air passage in the axial direction adjacently to the main inner air passage, and
the axial-direction rear end portion of the boundary wall is positioned forward of an axial-direction front end portion of the merging outer circumferential surface in the axial direction, and is positioned forward of an axial-direction front end portion of the merging inner circumferential surface in the axial direction.
5. The fuel injection device according to claim 3 , wherein
the main fuel injection port extends in the radial direction, and
the outlet of the main fuel injection port is positioned at the outward deflector.
6. The fuel injection device according to claim 1 , wherein
the main fuel injector includes:
a merging outer circumferential surface that demarcates the merged air passage and that is positioned rearward of the main outer air passage in the axial direction adjacently to the main outer air passage; and
a merging inner circumferential surface that demarcates the merged air passage and that is positioned rearward of the main inner air passage in the axial direction adjacently to the main inner air passage, and
an axial-direction rear end portion of the boundary wall is positioned forward of an axial-direction front end portion of the merging outer circumferential surface in the axial direction, and is positioned forward of an axial-direction front end portion of the merging inner circumferential surface in the axial direction.
7. The fuel injection device according to claim 6 , wherein
the main fuel injection port includes an outlet, and is configured to either:
inject the fuel, at a position where the outlet faces the merging outer circumferential surface, into the compressed air taken in by the main inner air passage; or
inject the fuel, at a position where the outlet faces the merging inner circumferential surface, into the compressed air taken in by the main outer air passage.
8. The fuel injection device according to claim 1 , wherein
the main fuel injection port extends in the radial direction, and
an outlet of the main fuel injection port is positioned at the outward deflector.
9. The fuel injection device according to claim 1 , wherein
the main fuel injector is spaced apart from the pilot fuel injector outward in the radial direction,
the fuel injection device comprises an air reservoir that is positioned between the pilot fuel injector and the main fuel injector and that temporarily stores the compressed air, and
the main inner air passage takes in the compressed air stored in the air reservoir through the inlet that is open toward the air reservoir and that is open inward in the radial direction.
10. The fuel injection device according to claim 1 , wherein the main fuel injector receives air only from the inlets of the main inner air passage and the main outer air passage facing either radially inward or radially outward.