Impingement cooled can combustor
A can combustor includes a generally cylindrical housing having an interior, an axis, and a closed axial end. The closed axial end includes means for introducing fuel to the housing interior. A generally cylindrical combustor liner is disposed coaxially within the housing and configured to define with the housing respective radially outer passages for combustion air and for dilution air, and also respective radially inner volumes for a combustion zone and a dilution zone. The combustion zone is disposed axially adjacent the closed housing end, and the dilution zone is disposed axially distant the closed housing end. The can combustor also includes an impingement cooling sleeve coaxially disposed between the housing and the combustor liner and extending axially from the closed housing end for a substantial length of the combustion zone. The sleeve has a plurality of apertures sized and distributed to direct combustion air against the radially outer surface of the portion of the combustor liner defining the combustion zone, for impingement cooling. Essentially all of the combustion air flows through the impingement cooling apertures prior to admission to the combustion zone. A small portion of the impingement cooling air may be used for film cooling of the liner proximate the closed housing end.
1. A can combustor comprising:
a generally cylindrical housing having an interior, an axis, and a closed axial end, the closed axial end including means for introducing fuel to the housing interior;
a generally cylindrical combustor liner disposed coaxially within the housing and configured to define with the housing respective radially outer passages for combustion air and for dilution air, and the liner also defining respective radially inner volumes for a combustion zone and a dilution zone, the combustion zone being disposed axially adjacent the closed housing end, and the dilution zone being disposed axially distant the closed housing end; and
a impingement cooling sleeve coaxially disposed between the housing and the combustor liner and extending axially from the closed housing end for a substantial length of the combustion zone to a sleeve closed end, the sleeve having a plurality of apertures sized and distributed to direct combustion air against the radially outer surface of the portion of the combustor liner defining the combustion zone for impingement cooling, the impingement cooled radial outer liner surface being imperforate,
wherein the flow of combustion air and dilution air in the radially outer passages is generally axially toward the closed housing end,
wherein the dilution air passage includes a plurality of dilution ports in the combustor liner for admitting dilution air radially into the dilution zone, and
wherein the combustor liner and the closed axial end are configured such that essentially all of the combustion air flows through the impingement cooling apertures prior to admission to the combustion zone.
2. The can combustor as in claim 1 , wherein a portion of the combustion air is further used for film cooling a constricted end of the liner proximate the closed housing end after the portion has traversed the impingement cooling apertures.
3. The can combustor as in claim 2 , wherein less than or equal to about 8% of the combustion air is used for film cooling.
4. The can combustor as in claim 1 , wherein the impingement cooling sleeve terminates at the liner at an axial position between the closed housing end and the dilution ports.
5. The can combustor as in claim 4 , wherein the impingement cooling sleeve is configured to seal off the combustion air from the dilution air passage after the combustion air has traversed the impingement cooling apertures.
6. The can combustor as in claim 1 , wherein the impingement cooling sleeve is generally cylindrical in shape.
7. The can combustor as in claim 1 , wherein the impingement cooling sleeve is frusto-conical in shape, with a larger diameter being disposed axially adjacent the closed housing end.
8. The can combustor as in claim 1 , wherein the combustion air portion of a total of the combustion air and the dilution air is between about 45-55%.