Jet engine nacelle with drag augmenter auxiliary for thrust-reverser system

Claim 1

A nacelle housing a jet propulsion engine equipped with a rearwardly-directed jet propulsion nozzle and a thrust-reverser system actuatable to deflect laterally the engine exhaust flow from said jet propulsion nozzle, said nacelle having a streamlined outer surface so designed that in normal operation the relative flow of boundary air adheres thereto along substantially all its fore-to-aft extension including a rearwardly tapering aft-section which ends with a trailing edge around said jet propulsion nozzle and which presents two successive annular peripheral zones, namely: a front annular peripheral zone located at a distance ahead of said trailing edge and comprising, in peripheral alternation, at least one thrust-reversal side outlet bounded circumferentially by two opposite arcuately-spaced edges and having a total passage area designed for issuing said laterally-deflected engine exhaust flow, and at least one solid impervious span between consecutive side outlet edges, extending over a sufficient segmentary extension of the periphery of said aft-section to shield effectively adjacent environment from said laterally-deflected engine exhaust flow, and a rear annular peripheral zone extending between said front annular peripheral zone and said trailing edge and having a solid continuous outer surface subdividable into peripherally alternate first and second segments which lie respectively in longitudinal rearward extension of said thrust-reversal side outlet and of said solid impervious span, whereby said impervious span and said second segment in longitudinal rearward extension thereof form together a longitudinally-continuous solid stretch of the outer surface of said rearwardly tapering aft-section, wherein the improvement comprises a controllable axuiliary device which is operatively associated with said solid stretch to act with respect thereto as a localized nacelle-streamlining destroyer, said device comprising: transiently activatable means located adjacent said solid impervious span and extending substantially between said side outlet edges for positively causing said relative boundary airflow to separate from said second segment lying in longitudinal rearward extension of said solid imperivous span, and control means for selectively activating said transiently activatable means in conjunction with the actuation of said thrust-reverser system, thereby switching said relative boundary airflow from an aerodynamic condition of flow adherence to said second segment, to an aerodynamic condition of flow separation therefrom.