| 摘要 |
A variable area nozzle for a gas turbine engine is provided that has a circumferential outer boundary (which may be formed at least in part by the nacelle of a turbofan engine) that has a fixed portion and a movable portion. The movable portion is movable by an actuator both upstream and downstream from a datum position. This allows the exit area of the variable area nozzle to be adjusted according to flight conditions. When the movable portion is at or upstream of the datum position, there is no flow path between the fixed and movable portions. This enables the nozzle exit area to be optimized throughout flight, for example during changing cruise conditions, without inducing unwanted and inefficient flow structures between the fixed and movable portions and without allowing flow to leak out of the outer boundary of the nozzle.
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