Combustor and gas turbine including the combustor
The upstream-side wall portion 54 includes, in the circumferential direction thereof, a first region 31 where air inlets 30 are formed at a lower density, and a second region 32 which is disposed at a position offset from the first region 31 in the circumferential direction, and in which the air inlets 30 are formed at a higher density than in the first region 31.
1. A combustor, comprising:
a plurality of fuel nozzles disposed in a circumferential direction;
a flame holding ring extending in the circumferential direction at a radially inner side of outlet portions of the plurality of fuel nozzles;
an upstream-side wall portion extending in the circumferential direction at an upstream side of the flame holding ring, the upstream-side wall portion having a plurality of air inlets for supplying air toward the flame holding ring via an annular space at the radially inner side of the outlet portions of the plurality of fuel nozzles,
wherein the upstream-side wall portion includes:
a plurality of first regions each having a first number of the plurality of air inlets, wherein each of the plurality of first regions extends circumferentially in a respective first range corresponding to a respective fuel nozzle position of each of the plurality of fuel nozzles; and
a plurality of second regions each having a second number of the plurality of air inlets with the second number higher than the first number;
wherein each of the plurality of second regions extends circumferentially in a respective second range corresponding to a respective circumferential position between a respective pair of adjacent fuel nozzles of the plurality of fuel nozzles such that each of the plurality of second regions alternates with each of the plurality of first regions in the circumferential direction, and in which the second number of the plurality of air inlets are formed at a higher density than a density of the first number of the plurality of air inlets, and
wherein a first spacing in the circumferential direction between each air inlet of the second number within a respective second region is smaller than a second spacing in the circumferential direction between any air inlet of the second number within the respective second region and any air inlet of the first number within an adjacent first region.
2. The combustor according to claim 1 ,
wherein the flame holding ring includes a first opening positioned at a downstream side of each of the second regions.
3. The combustor according to claim 2 ,
wherein the first opening includes at least one cut-out which is cut out from an outer peripheral edge of the flame holding ring to a position radially outward of an inner peripheral edge of the flame holding ring, toward an inner side of the flame holding ring in a radial direction.
4. The combustor according to claim 3 ,
wherein the cut-out has a maximum cut-out depth which is not greater than ⅔ of a distance between the outer peripheral edge and the inner peripheral edge in the radial direction of the flame holding ring.
5. The combustor according to claim 2 ,
wherein the first opening includes at least one through hole formed between an outer peripheral edge of the flame holding ring and an inner peripheral edge of the flame holding ring.
6. The combustor according to claim 1 , further comprising:
a plurality of partition members each extending along an axial direction in the annular space between the upstream-side wall portion and the flame holding ring, each of the plurality of partition members dividing the annular space circumferentially into a plurality of first spaces each corresponding to a respective first region of the plurality of first regions and a plurality of second spaces each corresponding to a respective second region of the plurality of the second regions, wherein each of the plurality of first spaces alternates with each of the plurality of second spaces in the circumferential direction.
7. The combustor according to claim 1 , further comprising:
a pilot cone having the flame holding ring at a downstream end; and
a cooling ring disposed at a radially outer side of the pilot cone and at the radially inner side of the outlet portions of the plurality of fuel nozzles,
wherein a gap is formed between the pilot cone and the cooling ring.
8. The combustor according to claim 7 ,
wherein the flame holding ring includes a plurality of first openings with each first opening of the plurality of first openings positioned at a respective downstream side of a respective second region of the plurality of second regions, and wherein the plurality of air inlets of the upstream-side wall portion and the plurality of first openings of the flame holding ring are in communication via a space at a radially outer side of the cooling ring and at the radially inner side of the outlet portions of the plurality of fuel nozzles.
9. The combustor according to claim 7 ,
wherein the upstream-side wall portion has a cooling air inlet which opens into the gap between the pilot cone and the cooling ring.
10. The combustor according to claim 7 ,
wherein the flame holding ring positioned at the downstream end of the pilot cone includes a plurality of first openings with each first opening of the plurality of first openings positioned at a respective downstream side of a respective second region of the plurality of second regions,
wherein the cooling ring includes a flange portion positioned at an upstream side of the flame holding ring, and
wherein the flange portion includes a plurality of second openings with each second opening of the plurality of second openings positioned at a respective upstream side of a respective first opening of the plurality of first openings of the flame holding ring.
11. The combustor according to claim 7 , further comprising:
at least one spacer portion for forming the gap between the pilot cone and the cooling ring.
12. The combustor according to claim 11 ,
wherein the cooling ring includes a flange portion positioned at an upstream side of the flame holding ring,
wherein the flange portion has a second opening corresponding to a first opening of the flame holding ring,
wherein the at least one spacer portion includes a plurality of protruding portions disposed on the flange portion so as to protrude downstream toward the flame holding ring, and
wherein the plurality of protruding portions include a pair of protruding portions positioned at either side of the second opening of the flange portion in the circumferential direction.
13. A gas turbine, comprising:
the combustor according to claim 1 ; and
a turbine configured to be driven by combustion gas from the combustor.