Turbo fan engine nacelle exhaust system with concave primary nozzle 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 (Rc). The core cowl has a distal end which is radially spaced from the outer surface of the primary plug by a distance ([H) in a direction perpendicular to the central axis. The primary nozzle plug and core cowl define a ratio Rc/[H between approximately 14 and 18. The distal end of the core cowl has a core cowl radius Rp with respect to the central axis. A discharge end of the fan nozzle sleeve has a fan nozzle sleeve radius Rf, wherein a ratio Rp/Rf is between approximately 0.4 and 0.6. The outer surface of the primary plug forms a primary plug angle öp between approximately 13 DEG and 19 DEG with respect to the central axis at the primary nozzle exit. The proper scaling of these key dimensions thereby defines a primary nozzle which reduces the shock associated noise of the turbo fan engine.