Combustion chamber for a gas turbine engine
A combustion chamber suitable for a gas turbine engine is provided with at least one Helmholtz resonator having a resonator cavity and a resonator neck in flow communication with the chamber interior. The resonator neck is provided with at least cooling holes extending through its wall for improved damping and cooling, at least one of the holes is directed towards the resonator cavity.
1. A combustion chamber for a gas turbine engine comprising at least one Helmholtz resonator having a resonator cavity and a resonator neck in flow communication with the interior of the combustion chamber, the neck having cooling holes extending through a wall thereof, at least one of the cooling holes having an axis that is directed towards the resonator cavity such that in use the cooling holes direct cooling air into the resonator cavity.
2. A combustion chamber according to claim 1 , comprising at least two Helmholtz resonators.
3. A combustion chamber according to claim 1 , wherein a plurality of cooling holes are provided in the wall of the neck.
4. A combustion chamber according to claim 1 , wherein the cooling holes are circumferentially spaced in one or more rows extending around the circumference of the neck.
5. A combustion chamber according to claim 4 , wherein at least two circumferential rows are provided and the rows are axially spaced.
6. A combustion chamber as claimed in claim 5 wherein the holes of a circumferential row towards the combustion chamber end of the neck are angled in a direction towards the combustion chamber end of the neck such that the respective axes of the holes converge in the direction of the combustion chamber.
7. A combustion chamber as claimed in claim 6 , wherein the angle of the holes with respect to the longitudinal axis of the neck is substantially in the range of 15 to 40 degrees.
8. A combustion chamber as claimed in claim 7 where the said angle is substantially 30 degrees.
9. A combustion chamber according to claim 6 , wherein the holes of a circumferential row towards the combustion chamber end of the neck is enclosed by a perforated screen for metering the air passing through the holes.
10. A combustion chamber as claimed in claim 1 , wherein the neck is tubular and said holes are angled with respect to the neck circumference.
11. A combustion chamber as claimed in claim 10 wherein the holes have a tangential component substantially in the range of 30 to 60 degrees with respect to the neck circumference.
12. A combustion chamber as claimed in claim 11 wherein the angle of the holes with respect to the neck circumference is substantially 45 degrees.
13. A Helmholtz resonator for a gas turbine engine combustion chamber; the said resonator having a resonator cavity and a resonator neck for flow communication with the interior of the combustion chamber, the neck having cooling holes extending through a wall thereof, at least one of the cooling holes having an axis that is directed towards the resonator cavity such that in use the cooling holes direct cooling air into the resonator cavity.