Sheared exhaust nozzle

Abstract

Conventional commercial engine exhaust systems are defined with axi-symmetric surfaces (e.g., conical or nearly conical surfaces), which create an annular exhaust for the fan (bypass) nozzle of roughly constant duct-height around the circumference. In one example configuration, the fan sleeve has been sheared upward (towards the wing or pylon) causing a larger area and duct height near the pylon relative to the portion away from the pylon. For a given thrust generated by the turbofan engine housed in the nacelle, the shear toward the pylon mount realigns the thrust in the direction of flight which may, in some examples, reduce noise experienced downstream of the turbofan engine and decreases fuel consumed in the engine core.

What is claimed is: 
     
         1 . An exhaust for an aircraft engine, comprising:
 a curved portion applying a shift to a thrust comprising a flow of a gas exiting through the exhaust, wherein the thrust comprises a thrust vector and the shift is in a direction that counteracts a deflection of the flow by a structure of an aircraft propelled by the aircraft engine, wherein:   the deflection is away from a first direction propelling the aircraft in a direction of flight, and   the shift counteracts the deflection so as to increase an alignment of the thrust vector with the first direction.   
     
     
         2 . The exhaust of  claim 1 , wherein the aircraft comprises a fuselage and the structure comprises a mount mounting the aircraft engine to the fuselage. 
     
     
         3 . The exhaust of  claim 2 , wherein the aircraft engine is mounted on the fuselage and not a wing of the aircraft. 
     
     
         4 . The exhaust of  claim 3 , wherein the structure comprises a pylon. 
     
     
         5 . The exhaust of  claim 4 , wherein the deflection comprises turning the flow in a sideways direction that does not provide lift or provide thrust in the first direction. 
     
     
         6 . The exhaust of  claim 5 , wherein the shift increases the alignment so that the turning does not need to be counteracted by an engine on another side of the aircraft. 
     
     
         7 . The exhaust of  claim 1 , wherein the shift aligns the thrust vector with the first direction. 
     
     
         8 . The aircraft comprising the exhaust of  claim 1 . 
     
     
         9 . The aircraft engine, comprising the exhaust of  claim 1 , comprising:
 a nacelle comprising an inlet;   a pylon attached to the nacelle;   an engine core housed in the nacelle, the engine core connected to a core exhaust;   a fan housed in the nacelle so as to draw a first portion of air through the inlet into the engine core and draw a second portion of the air through the inlet into a fan duct between the engine core and the nacelle; and wherein:   the fan duct has an outer flow surface on the nacelle and an inner flow surface opposite the outer flow surface, the outer flow surface and the inner flow surface bounding a flow of the second portion of the air;   the first portion of air is used to burn fuel in the engine core so as to form a first exhaust gas exhausted through the core exhaust;
 the fan duct comprises a fan exhaust and the second portion of the air is exhausted as a second exhaust gas through the fan exhaust, wherein the flow of gas comprises a second exhaust gas generating the thrust comprising the thrust vector; and 
   the outer flow surface comprises the curved portion such that:
 a first distance between a first point at a trailing edge on the outer flow surface and a second point on the inner flow surface is larger than a second distance between a third point on the trailing edge of the outer flow surface and a fourth point on the inner flow surface, 
 the first distance is in a first region between the pylon and the core exhaust; 
 the second distance is in a second region between the core exhaust and a section of the nacelle facing away from an aircraft propelled using the engine. 
   
     
     
         10 . The engine of  claim 9 , wherein:
 the curved portion includes:
 a first shift in a first position of the first point by 1%-2% of a diameter of the fan exhaust, as measured at the trailing edge, 
 a second shift in a second position of the third point by 1%-2% of the diameter of the fan exhaust, as measured at the trailing edge, and 
 the first shift and the second shift are relative to the first position of the first point and the second position of the third point, respectively, when the fan exhaust and the core exhaust are concentric or the first distance is equal to the second distance. 
   
     
     
         11 . The engine of  claim 9 , wherein the fan exhaust comprises a fan nozzle and a shear in a plane forming a cross section through the pylon and the fan nozzle, so that the shear forms the curved portion. 
     
     
         12 . The engine of  claim 9 , wherein:
 the curved portion shifts the second exhaust gas in the direction having a component towards the pylon so as to provide the alignment of the thrust vector in the direction of the flight.   
     
     
         13 . The engine of  claim 9 , wherein the engine comprises a geared turbofan engine and the nacelle forms a tighter wrap around the engine core as compared to the nacelle without the curved portion, thereby reducing aerodynamic drag of the engine. 
     
     
         14 . The exhaust of  claim 1 , wherein the shift reduces noise experienced downstream of the aircraft. 
     
     
         15 . A method of making an aircraft engine, comprising:
 forming an exhaust comprising a curved portion applying a shift to a thrust comprising a flow of a gas exiting through the exhaust, wherein the thrust comprises a thrust vector and the shift is in a direction that counteracts a deflection of the flow by a structure of an aircraft propelled by the aircraft engine, wherein:   the deflection is away from a first direction propelling the aircraft in a direction of flight, and   the shift counteracts the deflection so as to increase an alignment of the thrust vector with the first direction.   
     
     
         16 . The method of  claim 15 , wherein the aircraft comprises a fuselage and the structure comprises a mount mounting the aircraft engine to the fuselage. 
     
     
         17 . The method  claim 15 , further comprising mounting the aircraft engine on a fuselage and not a wing of the aircraft. 
     
     
         18 . The method of  claim 17 , wherein the structure comprises a pylon. 
     
     
         19 . The method of  claim 15 , wherein the deflection comprises turning the flow in a sideways direction that does not provide lift or provide thrust in the first direction. 
     
     
         20 . The method of  claim 15 , wherein the shift aligns the thrust vector with the first direction.