Device for supplying secondary air in a gas turbine engine

Abstract

In a device for supplying secondary air in a gas turbine engine provided with an inner shaft () and a hollow outer shaft () coaxially nested with each other, a seal air introduction passage () is defined inside the engine for introducing a part of high pressure air drawn from a high pressure compressor into a seal section provided in each of the bearing boxes for supporting the inner and outer shafts; and a swirl air cooling turbine () is provided in the seal air introduction passage and attached to a part attached to the outer shaft in a rotationally fast manner. The swirl air cooling turbine () is formed around a section of the outer shaft intermediate between the high pressure compressor and the high pressure turbine, the swirl air cooling turbine including a spiral flow path extending in a substantially cylindrical plane coaxial with the outer shaft. Because the high pressure swirl air is cooled by the swirl air cooling turbine provided in a radially central part, the energy of the swirl air is effectively expended, and this prevents the generation of a stagnation zone. Thereby, the secondary air can be favorably cooled before it is forwarded to the user such as the bearing boxes without causing an undue rise in the pressure of the impeller back chamber.