Gas turbine engine transition ducts

Abstract

A gas turbine engine transition duct 34 is used to convey exhaust gas and bypass air away from the engine, towards an exhaust nozzle (not shown). The duct 34 defines the outer extremity of the path for gas and/or air through the duct. The duct comprises a plurality of flat panel members 36 which together define the outer extremity of the path.

1 . A gas turbine engine transition duct through which, in use, exhaust gas and bypass air are conveyed away from the engine toward an exhaust nozzle, the duct defining the outer extremity of the path for gas and/or air through the duct, and the duct comprising a plurality of flat panel members which together define the outer extremity of the path, wherein
 a plurality of primary flat panel members extend downstream from a duct inlet which is narrower than the cross-section defined by the primary panel members, along at least one axis; and   guide panels located around the inlet, each guide panel being a flat panel member and the guide panels being oriented to widen the path from the inlet toward the outer extremity defined by the primary flat panel members.   
     
     
         2 . A duct according to  claim 1 , wherein the plurality of primary flat panel members have respective downstream edges defining a substantially polygonal duct outlet. 
     
     
         3 . A duct according to  claim 2 , comprising four primary flat panel members which have respective downstream edges defining a substantially rectilinear duct outlet. 
     
     
         4 . A duct according to  claim 1  wherein the plurality of primary flat panel members together define a substantially polygonal cross-section, perpendicular to the flow direction, during use. 
     
     
         5 . A duct according to  claim 4 , comprising four primary flat panel members which together define a substantially rectilinear cross-section, perpendicular to the flow direction, during use. 
     
     
         6 . A duct according to  claim 1 , wherein the guide panels are oriented to be oblique to the primary flat panel members. 
     
     
         7 . A duct according to  claim 1 , further comprising guide vanes positioned around the duct inlet to direct incoming bypass air outwardly toward the primary panel members. 
     
     
         8 . A duct according to  claim 7 , wherein the guide vanes are positioned to direct bypass air across the guide panels. 
     
     
         9 . A duct according to  claim 7 , wherein the guide vanes are shaped to follow at least part of the outline of the duct inlet, at a substantially constant separation when viewed along the duct. 
     
     
         10 . A duct according to  claim 1 , comprising a liner defining an inner path for exhaust gases within an outer path for bypass air.