TURBO FAN ENGINE NACELLE EXHAUST SYSTEM WITH CONCAVE PRIMARYNOZZLE PLUG

摘要

A turbo fan engine nacelle houses an engine which forces engine exhaust through a primary nozzle and a fan nozzle positioned along a common central axis. The primary nozzle is bordered interiorly by a primary nozzle plug and bordered exteriorly by a primary nozzle sleeve. The fan nozzle is bordered interiorly by a core cowl and bordered exteriorly by a fan nozzle sleeve. The primary nozzle plug includes a generally cone shaped outer surface which is concave when viewed in side elevation. The concave outer surface has a radius of curvature (R c) . The core cowl has a distal end which is radially spaced from the outer surface o f the primary plug by a distance (.DELTA.H) in a direction perpendicular to the central axis. The primary nozzle plug and core cowl define a ratio R c/.DELTA.H between approximately 14 and 18. The distal end of the core cowl has a core cowl radius R p with respect to the central axis. A discharge end of the fan nozzle sleeve has a fan nozzle slee ve radius R f, wherein a ratio R p/R f is between approximately 0.4 and 0.6. The outer surface of the primary plug forms a primary plug angle ~p between approximately 13.degree. and 19.degree. with respect to the central axis at the primary nozzle exit. The proper scaling of these key dimensions thereby defines a primary nozzlewhich reduces the shock associated noise of the turbo fan engine.