Device for efficient usage of cooling air for acoustic damping of combustion chamber pulsations
View Patent ↗Combustion driven pressure pulsations may limit the range of operating conditions where a modern gas turbine can operate with low emission and high efficiency performance. The control of acoustic vibrations has been consequently growing as an essential issue in gas turbine design, development and maintenance. The basic idea of the present invention is to use cooling air leakage through the gaps ( 7 ) of combustor liner segments ( 3;4 ) to get acoustic damping of combustion pulsations. The main component of the design is the sealing device ( 8 ) which covers the gap ( 7 ) between the two liner segments ( 3 ) and ( 4 ). The sealing device ( 8 ) collects in the plenum ( 9 ) some of the cooling air ( 6 ) flowing between the outer casing ( 1 ) and the inner liner structure ( 2 ). For this purpose the sealing device ( 8 ) is provided with openings ( 12 ) along the side walls ( 10 ) which allow the cooling air ( 6 ) to enter the plenum ( 9 ). In the plenum ( 9 ) the cooling air ( 6 ) is distributed along the gap ( 7 ) and discharged through openings ( 13 ), distributed along the top side ( 11 ) of the sealing device ( 8 ). The jets ( 18 ) discharged through the openings ( 13 ) achieve the additional effect to dampen acoustic pulsations in the combustion chamber ( 17 ).
1. A combustion chamber for a gas turbine, said combustion chamber comprising:
a casing forming an outer structure of the combustion chamber;
a liner structure spaced radially inwardly from the casing and forming an inner surface of the combustion chamber casing, said liner structure comprising a plurality of segments and a gap between adjacent segments;
a cooling air duct between the casing and the liner segments;
a sealing device in the gap between adjacent segments having a multiplicity of outlet openings to discharge jets of cooling air into the combustion chamber; and
wherein the sealing device comprises a first side wall and a second side wall, both side walls arranged in the area of the cooling air duct, a third wall on a top side bridging the gap, a plenum formed by the side walls and the top wall, inlet openings along the side walls, and outlet openings along the top side in the area of the gap.
2. The combustion chamber according to claim 1 , wherein the total area of the outlet openings is smaller than the total area of the inlet openings.
3. The combustion chamber according to claim 1 , wherein both the outlet openings and the inlet openings comprise cylindrical holes.
4. A system comprising:
a gas turbine including an annular combustion chamber; wherein the annular combustion chamber comprises a combustion chamber according to claim 1 .