Gas turbine engine exhaust nozzle

Abstract

A gas turbine engine exhaust nozzle for reducing exhaust noise comprising a substantially frusto-conical nozzle wall, and a plurality of circumferentially disposed nozzle tabs which extend in a generally downstream direction from a downstream periphery of the nozzle wall. The nozzle tabs are radially inwardly angled at an angle (β) of up to 20°, but preferably up to 10°, relative to the nozzle wall. Preferably tabs are of a substantially trapezoidal shape and substantially trapezoidally shaped notches are defined between adjacent tabs. Substantially V shaped notches may however be defined between the tabs. The angled tabs are particularly suitable for a ducted fan gas turbine engine and can be provided on the core exhaust nozzle or the bypass exhaust nozzle or on both nozzles. A bypass exhaust nozzle with such angled tabs can also be used with a lobed core exhaust nozzle.

We claim:  
     
         1 . A gas turbine engine exhaust nozzle comprising a substantially frusto-conical nozzle wall having a downstream periphery, and a plurality of circumferentially disposed nozzle tabs, the nozzle tabs extend in a generally downstream direction from the downstream periphery of the nozzle wall; 
 wherein the nozzle tabs are radially inwardly angled at an angle of up to 20° relative to the nozzle wall.    
     
     
         2 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the tabs circumferentially taper in a downstream direction.  
     
     
         3 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the tabs are of a substantially trapezoidal shape.  
     
     
         4 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the tabs are of a substantially rectangular or square shape.  
     
     
         5 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the tabs are circumferentially disposed about the periphery of the nozzle to define substantially trapezoidally shaped notches between adjacent tabs.  
     
     
         6 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the tabs are circumferentially disposed about the periphery of the nozzle to define substantially V shaped notches between adjacent tabs.  
     
     
         7 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the edges of the tabs are curved.  
     
     
         8 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the nozzle tabs are radially inwardly angled at an angle of up to 10° relative-to the nozzle wall.  
     
     
         9 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the exhaust nozzle is a core engine nozzle.  
     
     
         10 . A gas turbine engine exhaust nozzle as claimed in  claim 1  in which the exhaust nozzle is a bypass exhaust nozzle.  
     
     
         11 . A ducted fan gas turbine engine exhaust nozzle assembly as claimed in  claim 1 , the assembly comprising a core exhaust nozzle and a bypass exhaust nozzle.  
     
     
         12 . A ducted fan gas turbine engine exhaust nozzle assembly nozzle as claimed in  claim 1  comprising an outer bypass exhaust and an inner core exhaust nozzle of a lobed mixer type.  
     
     
         13 . A ducted fan gas turbine engine exhaust nozzle assembly as claimed in  claim 12  in which the downstream end of the bypass nozzle is further downstream than the downstream periphery of the core exhaust nozzle.  
     
     
         14 . A ducted fan gas turbine engine exhaust nozzle assembly as claimed in  claim 10  in which the downstream end of the bypass nozzle is upstream of the downstream periphery of the core exhaust nozzle.