| 摘要 |
A method is disclosed for discharging combustion gases from an engine powering an aircraft at subsonic and supersonic velocities. The engine includes a variable area exhaust nozzle having primary and secondary flaps defining a generally converging channel and exhaust channel, respectively, for the combustion gases. The method comprises the steps of contouring the secondary flaps to a first contour at a first position at a first value of a nozzle pressure ratio NPR across the converging and exhaust channels. The method further includes the step of contouring the secondary flaps to a second contour at a second position at a second value of NPR. In a preferred embodiment, the first contour is straight at low values of NPR and the second contour is generally concave for high values of NPR. Preferred embodiments of an exhaust nozzle for carrying out the method include the secondary flaps taking the form of a plurality of articulated secondary flap segments which are positionable collectively to form a straight contour of low NPR values and to form a generally concave contour at relatively high NPR values.
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