Gas turbine engine assembly and method of assembling same

Abstract

A method of assembling a gas turbine assembly includes providing a core gas turbine engine including a high-pressure compressor, a combustor, and a turbine, coupling a. A low-pressure turbine is axially aft from the core gas turbine engine, coupling a fan assembly is axially forward from the core gas turbine engine, and coupling a booster compressor is coupled to the low-pressure turbine such that the booster compressor and the low-pressure turbine rotate at a first rotational speed, and an epicyclic gearbox is coupled to the low-pressure turbine and the fan assembly such that the fan assembly rotates at a second rotational speed.

What is claimed is: 
     
         1 . A method of assembling a gas turbine engine assembly, said method comprising:
 providing a core gas turbine engine including a high-pressure compressor, a combustor, and a turbine;   coupling a low-pressure turbine axially aft of the core gas turbine engine;   coupling a fan assembly axially forward of the core gas turbine engine; and   coupling a booster compressor to the low-pressure turbine; and coupling the fan assembly to the booster compressor via a gearbox and a drive shaft such that, upon rotation of the drive shaft in a first rotational direction, the booster compressor and the low-pressure turbine rotate in the first rotational direction at a first rotational speed and the fan assembly rotates in a second rotational direction at a second rotational speed, the first rotational direction different than the second rotational direction, the first rotational speed greater than the second rotational speed.   
     
     
         2 . A method in accordance with  claim 1  further comprising:
 wherein coupling the fan assembly to the booster compressor via a gearbox comprises coupling the gearbox between the driveshaft and the fan assembly. 
 
     
     
         3 . A method in accordance with  claim 2  further comprising coupling a first thrust bearing assembly between the drive shaft and the gearbox such that thrust loads generated by the low-pressure turbine and the booster compressor are transferred to ground. 
     
     
         4 . A method in accordance with  claim 2  further comprising coupling a second thrust bearing assembly between the gear-box and the fan assembly such that thrust loads generated by the fan assembly are transferred to ground. 
     
     
         5 . A method in accordance with  claim 2  wherein coupling a gearbox further comprises providing the gearbox with a substantially toroidal cross-sectional profile between the fan assembly and the drive shaft such that the gearbox substantially circumscribes the drive shaft. 
     
     
         6 . A method in accordance with  claim 1  further comprising:
 coupling a gearbox to the fan assembly; and 
 coupling a flex connection between the drive shaft and the gearbox. 
 
     
     
         7 . A method in accordance with  claim 1  wherein coupling a booster compressor to the low-pressure turbine further comprises coupling the booster compressor to the low-pressure turbine with the booster compressor including a predetermined quantity of compressor stages that is based on a compression ratio of the fan assembly and an overall compression ratio of the gas turbine engine assembly. 
     
     
         8 . A method in accordance with  claim 1  wherein coupling a booster compressor to the low-pressure turbine further comprises providing the booster compressor with less than four booster stages. 
     
     
         9 . A turbine engine assembly comprising:
 a core gas turbine engine comprising a high-pressure compressor, a combustor, and a high-pressure turbine coupled together in a serial flow relationship;   a low-pressure turbine coupled to a drive shaft and located axially aft of said the core gas turbine engine; a fan assembly coupled axially forward of said core gas turbine engine; and   a booster compressor coupled to said the low-pressure turbine via the drive shaft and a shaft extension; and   the shaft extension having a forward end coupled to the booster compressor and a rear end coupled to the drive shaft by a plurality of splines;   an epicyclic gearbox with an output and an input, the input being coupled to the shaft extension;   a fan assembly coupled axially forward of the core gas turbine engine, the fan assembly being coupled to a the booster compressor via a the epicyclic gearbox and the shaft extension coupled to the drive shaft;   a sump within which the epicyclic gearbox is located such that lubrication fluid in the sump lubricates at least portions of the epicyclic gearbox;   a pair of labyrinth seals positioned between the booster compressor and the sump to facilitate sealing an upstream side of the booster compressor from the sump;   a first thrust bearing assembly aft of the epicyclic gearbox, the first thrust bearing assembly being mounted between the shaft extension and a frame of the core gas turbine engine;   a second thrust bearing assembly forward of the epicyclic gearbox, the second thrust bearing assembly being positioned between the fan assembly and the output of the epicyclic gearbox; and   the first thrust bearing assembly further comprising an inner race radially positioned between the shaft extension and an outer race, the inner race being configured to rotate about a longitudinal axis of the turbine engine assembly and the outer race being coupled to the framesuch that,   wherein the epicyclic gearbox is coupled between the shaft extension and the fan assembly, and upon rotation of saidthe drive shaft in a first rotational direction, saidthe booster compressor and saidthe low-pressure turbine rotate in the first rotational direction at a first rotational speed and saidthe fan assembly rotates in a second rotational direction at a second rotational speed, the first rotational direction different than the second rotational direction, the first rotational speed greater than the second rotational speed,   wherein the shaft extension is coupled to the booster compressor forward of a forward end of the drive shaft.   
     
     
         10 . A turbine engine assembly in accordance with  claim 9  wherein said gearbox is coupled between said drive shaft and said fan assembly. 
     
     
         11 . A turbine engine assembly in accordance with  claim 10  further comprising a first thrust bearing assembly coupled between said drive shaft and said gearbox and configured to transfer thrust loads generated by said low-pressure turbine and said booster compressor to ground. 
     
     
         12 . A turbine engine assembly in accordance with  claim 10  further comprising a second thrust bearing assembly coupled between said gearbox and said fan assembly and configured to transfer thrust loads generated by said fan assembly to ground. 
     
     
         13 . A turbine engine assembly in accordance with  claim 10  wherein said gearbox has a substantially toroidal cross-sectional profile and substantially circumscribes said drive shaft. 
     
     
         14 . A turbine engine assembly in accordance with  claim 10  further comprising a frame configured to support said fan assembly and said gearbox, said frame configured to carry said fan assembly radial, thrust, and overturning moment to an outer engine structure and mounts. 
     
     
         15 . A turbine engine assembly in accordance with  claim 9  further comprising:
 a flex connection coupled between said drive shaft and said gearbox. 
 
     
     
         16 . A turbine engine assembly in accordance with  claim 9  wherein said booster compressor comprises a predetermined quantity of compressor stages that is based on a compression ratio of said fan assembly and an overall compression ratio of said gas turbine engine assembly. 
     
     
       17. The turbine engine assembly of  claim 9 , wherein the booster compressor has less than four stages of rotor blades. 
     
     
       18. The turbine engine assembly of  claim 17 , wherein the booster compressor has two stages of rotor blades. 
     
     
       19. The turbine engine assembly of  claim 9 , wherein the low-pressure turbine has four stages. 
     
     
       20. A turbine engine assembly comprising:
 a core gas turbine engine comprising a high-pressure compressor, a combustor, and a high-pressure turbine coupled together in a serial flow relationship;   a low-pressure turbine coupled to a drive shaft and located axially aft of the core gas turbine engine, the low-pressure turbine having four stages;   a fan assembly coupled to a frame and located axially forward of the core gas turbine engine;   a booster compressor coupled to the low-pressure turbine via the drive shaft and a shaft extension, the booster compressor having less than four stages;   the shaft extension having a forward end coupled to the booster compressor and a rear end coupled to the drive shaft by a plurality of splines, the shaft extension being positioned radially outward of the drive shaft;   a cone with a forward end and an aft end, the forward end of the cone being coupled to the forward end of the shaft extension and the aft end of the cone being coupled to a rotor disk of the booster compressor; and   an epicyclic gearbox with an input coupled to the shaft extension;   wherein the fan assembly is coupled to the booster compressor via the epicyclic gearbox and the shaft extension coupled to the drive shaft, and   wherein upon rotation of the drive shaft in a first rotational direction, the booster compressor and the low-pressure turbine rotate in the first rotational direction at a first rotational speed and the fan assembly rotates in a second rotational direction at a second rotational speed, the first rotational direction different than the second rotational direction, the first rotational speed greater than the second rotational speed.   
     
     
       21. The turbine engine assembly of  claim 20 , further comprising at least one roller element mounted between an output of the epicyclic gearbox and the frame. 
     
     
       22. The turbine engine assembly of  claim 20 , wherein the booster compressor has two stages. 
     
     
       23. The turbine engine assembly of  claim 20 , further comprising a first thrust bearing assembly mounted to the shaft extension,
 wherein the forward end of the cone is coupled to the forward end of the shaft extension at a location forward of the first thrust bearing assembly.   
     
     
       24. A turbine engine assembly comprising:
 a core gas turbine engine comprising a high-pressure compressor, a combustor, and a high-pressure turbine coupled together in a serial flow relationship;   a low-pressure turbine coupled to a drive shaft and located axially aft of the core gas turbine engine, the low-pressure turbine having four stages;   a fan assembly coupled axially forward of the core gas turbine engine;   a booster compressor coupled to the low-pressure turbine via the drive shaft and a shaft extension coupled to the drive shaft;   an epicyclic gearbox with an input coupled to the shaft extension;   a sump within which the epicyclic gearbox is located such that lubrication fluid in the sump lubricates at least portions of the epicyclic gearbox; and   a pair of labyrinth seals that facilitate sealing an upstream side of the booster compressor from the sump;   wherein the fan assembly is coupled to the booster compressor via the epicyclic gearbox and the shaft extension coupled to the drive shaft, and   wherein upon rotation of the drive shaft in a first rotational direction, the booster compressor and the low-pressure turbine rotate in the first rotational direction at a first rotational speed and the fan assembly rotates in a second rotational direction at a second rotational speed, the first rotational direction different than the second rotational direction, the first rotational speed greater than the second rotational speed.   
     
     
       25. The turbine engine assembly of  claim 24 , wherein the booster compressor has less than four stages of rotor blades. 
     
     
       26. The turbine engine assembly of  claim 24 , wherein the booster compressor has two stages of rotor blades.