A gas turbine ( 1 ) includes a combustion chamber ( 2 ) followed by a stator airfoil row ( 4 ) defining a plurality of guide vanes and separated by the combustion chamber ( 2 ) by a first gap ( 5 ), and a rotor airfoil row ( 6 ) separated by the stator airfoil row ( 4 ) by a second gap ( 7 ). The stator airfoils ( 15 ) of the stator airfoil row ( 4 ) are connected to guide vane boxes ( 17 ) collecting a cooling fluid (A) and injecting it through nozzles ( 20 ) in the second gap ( 7 ) to make it to enter rotor airfoil inlets ( 23 ). The guide vane boxes ( 23 ) are provided with passages ( 30 ) connecting a zone ( 31 ) upstream of the guide vane boxes ( 17 ) to a zone ( 32 ) of the second gap ( 7 ) downstream of the guide vane boxes ( 32 ). Moreover, the mouths ( 3 ) of the passages ( 30 ) facing the rotor airfoil row ( 6 ) are closer to a hot gases path than the nozzles ( 20 ).
1. A gas turbine, comprising:
a combustion chamber;
a compressor for supplying cooling air and air to be mixed with fuel and combusted;
a stator airfoil row defining a plurality of guide vanes and guide vane boxes wherein the stator airfoil row is separated from the combustion chamber by a first gap;
a rotor airfoil row separated from the stator airfoil row by at least a second gap, the rotor airfoil row including rotor airfoil inlets, wherein the stator airfoils of the stator airfoil row are connected to the guide vane boxes;
a hot gas flow path through which hot gases formed in the combustion chamber pass through the stator airfoil row and the rotor airfoil row,
wherein the guide vane boxes include nozzles, the guide vane boxes being configured and arranged to collect cooling air and inject it through the nozzles into said second gap to make the cooling air enter the rotor airfoil inlets,
wherein said guide vane boxes comprise passages connecting a zone upstream of the guide vane boxes to a zone of the second gap downstream of the guide vane boxes such that compressed air diverted from the compressor and injected into the first gap moves out from the passages through passage mouths which are positioned at the second gap in a zone from where the injected compressed air cannot enter the rotor airfoil inlet, wherein each passage includes an upstream passage mouth opposite to the rotor airfoil row and at said zone upstream of the guide vane boxes;
a fixed frame; and
a first seal downstream of the upstream passage mouths between the guide vane boxes and the fixed frame and a second seal upstream of the upstream passage mouths between stator airfoil end walls and the fixed frame for sealing the first gap from the second gap.
2. A gas turbine as claimed in claim 1 , wherein said passage mouths are as close as, or closer than, the rotor airfoil inlet to the hot gas flow path.
3. A gas turbine as claimed in claim 1 , wherein the guide vane boxes comprise sidewalls, and said passages are defined by slots at said sidewalls.
4. A gas turbine as claimed in claim 1 , wherein said passages extend inside of the guide vane boxes.
5. A gas turbine as claimed in claim 4 , further comprising pipes defining said passages.
6. A gas turbine as claimed in claim 1 , wherein passage mouths facing the rotor airfoil row are closer to a hot gas flow path than said nozzles.
7. A gas turbine as claimed in claim 1 , wherein the passages connecting the zone upstream of the guide vane boxes to the zone of the second gap downstream of the guide vane boxes bypass a volume of the guide vane boxes for collecting the cooling fluid.
8. A gas turbine as claimed in claim 1 , wherein the guide vanes comprise a platform having an extension which extends to at least partly close the second gap separating the rotor airfoil row from the stator airfoil row, and wherein the mouths of the passages connecting a zone upstream of the guide vane boxes to a zone of the second gap downstream of the guide vane boxes are radially inside the platform extension on a side facing away from the hot gas flow path.