Method and device to cool the casing of turbojet engines

Cooling air is branched-off from a bypass flow and fed to the outside of the housing (1) via an intake channel (8) with shut-off valve (5). The air is introduced into a first chamber (6), where its volume is divided. Part of the air is fed from the chamber to the outside of the housing, while a second part is fed into a second chamber (7), behind the first, and then to the outside of the housing. The chambers are formed as buffer chambers, and the air is extracted via throttles.