A Proposed Extension to Algol 60

Air is bled from the compressor of a gas turbine engine and it is led to holes in the shanks of turbine blades, so as to cool the interiors of the blades during operation of the engine. Some of the air leaks radially outwards, to seal the gas annulus against hot gas leaks onto the face of the turbine disc. A reduced flow of cooling air is enabled at conditions other than engine full throttle. This however, starves the gas sealing air. The invention provides a back up supply, by putting the air through a plenum chamber and dividing it so that when cooling airflow is reduced, a further sealing air flow is provided in compensation therefore.