Ducted fan turbine engine for civil transport airplane, has orifice whose area is adapted to reference value of expansion ratio comprised between extreme values of ratios respectively corresponding to starting and ending of cruising phase

摘要

The engine has a cooling air nozzle (T) with a throat arranged before a cooling air outlet orifice (6). An annular section of the throat has a nominal area fixed by thermodynamic cycle of the engine and lower than an area of the orifice such that a convergent-divergent nozzle (15) is formed at a rear part of an annular cooling air channel (12). The area of the orifice is adapted to a reference value of an expansion ratio of cooling air (9) comprised between extreme values of expansion ratios respectively corresponding to starting and ending of a cruising phase. An independent claim is also included for a method for improving performances of a ducted fan turbine engine that is mounted on an aircraft before accomplishing a determined flight mission.