Air inlet for a gas turbine engine

Abstract

A radial air inlet for a gas turbine engine. The air inlet has an inlet duct defined between two axially-spaced radially-extending annular walls and has a plurality of circumferentially-spaced axially-extending struts extending between the annular walls adjacent a radially-outer portion of the air inlet. At least one of the struts has an internal passage extending between a first opening in a forward end of the strut and a second opening in an aft end of the strut, the first and second openings being axially spaced apart. A transmission shaft extends through the internal passage of said strut.

The invention claimed is: 
     
       1. A gas turbine engine, comprising:
 a compressor section and a turbine section drivingly engaged with a drive shaft, the drive shaft being rotatable about a center axis of the gas turbine engine; 
 a radial air inlet in fluid communication with the compressor section, the radial air inlet having an inlet duct defined between two axially-spaced radially-extending annular walls and having a plurality of circumferentially-spaced axially-extending struts extending between the annular walls adjacent a radially-outer portion of the air inlet, at least one of the struts having an internal passage extending between a first opening in a forward end of the strut and a second opening in an aft end of the strut, the first and second openings being axially spaced apart; and 
 a transmission shaft extending through the internal passage of said strut. 
 
     
     
       2. The gas turbine engine as defined in  claim 1 , wherein the first and second openings in said strut are aligned along a substantially axial direction, the transmission shaft extending through the openings in the substantially axial direction. 
     
     
       3. The gas turbine engine as defined in  claim 1 , wherein the transmission shaft is mechanically coupled at a first end to a first rotatable load of the gas turbine engine disposed on one side of the inlet duct, and mechanically coupled at a second end to a second rotatable load disposed on another side of the inlet duct, the first load includes the drive shaft and the second rotatable load includes an accessory gearbox of the gas turbine engine, the drive shaft being disposed forward of the radial air inlet, and the accessory gearbox being disposed aft of the radial air inlet. 
     
     
       4. The gas turbine engine as defined in  claim 3 , wherein the first rotatable load includes a tower shaft mechanically coupled at a first end to the first end of the transmission shaft, a second end of the tower shaft being mechanically coupled to the drive shaft. 
     
     
       5. The gas turbine engine as defined in  claim 1 , further comprising first and second bearings supporting the transmission shaft, the first bearing disposed on a side of one of the annular walls outside the inlet duct adjacent to said strut, and the second bearing disposed on a side of the other annular wall outside the inlet duct adjacent to said strut. 
     
     
       6. The gas turbine engine as defined in  claim 5 , wherein the first and second bearings are aligned along a substantially axial direction. 
     
     
       7. The gas turbine engine as defined in  claim 1 , wherein the inlet duct includes an air opening being defined between the annular walls at the radially outer portion of the air inlet, the air opening extending through an outermost surface of the engine. 
     
     
       8. The gas turbine engine as defined in  claim 1 , wherein at least one of the struts has an airfoil shape. 
     
     
       9. The gas turbine engine as defined in  claim 8 , wherein said strut having the airfoil shape includes a leading edge and a trailing edge, the trailing edge being radially closer to the center axis than the leading edge, a chord of said strut extending in a substantially radial direction between the leading and trailing edges. 
     
     
       10. The gas turbine engine as defined in  claim 1 , wherein each strut has an axial span defined between the annular walls of the inlet duct, and a radial span defined between an outer edge and an inner edge, the inner edge being radially closer to the center axis than the outer edge. 
     
     
       11. A drive system for a gas turbine engine, comprising:
 an inlet duct having two annular walls disposed about a center axis, each wall extending between an outer portion and an inner portion, the inner portion being radially closer to the center axis than the outer portion, the walls being axially spaced apart and defining an annular air passage between the walls; 
 a plurality of struts being circumferentially spaced-apart within the inlet duct, each strut extending between the annular walls and through the annular air passage, one of the struts having an internal passage extending between a first opening in a forward end of the strut and a second opening in an aft end of the strut, the first and second openings being axially spaced apart; and 
 a transmission shaft extending through the internal passage and the first and second openings of said strut. 
 
     
     
       12. The drive system as defined in  claim 11 , wherein the first and second openings in said strut are aligned along a substantially axial direction, the transmission shaft extending through the openings in the substantially axial direction. 
     
     
       13. The drive system as defined in  claim 11 , wherein at least one of the struts has an airfoil shape. 
     
     
       14. The drive system as defined in  claim 13 , wherein said strut having the airfoil shape includes a leading edge and a trailing edge, the trailing edge being radially closer to the center axis than the leading edge, a chord of said strut extending in a substantially radial direction between the leading and trailing edges. 
     
     
       15. The drive system as defined in  claim 11 , wherein each strut has an axial span defined between the annular walls of the inlet duct, and a radial span defined between an outer edge and an inner edge, the inner edge being radially closer to the center axis than the outer edge. 
     
     
       16. A method of operating a gas turbine engine, comprising:
 drawing air from a radially-outer portion of a radial air inlet of the engine to a radially-inner portion of the radial air inlet, the radial air inlet having circumferentially spaced-apart struts; and 
 driving a rotatable load of the engine with a transmission shaft extending across the radial air inlet and through one of the struts. 
 
     
     
       17. The method as defined in  claim 16 , wherein driving the rotatable load includes driving the rotatable load with the transmission shaft being oriented in a substantially axial direction. 
     
     
       18. The method as defined in  claim 16 , further comprising supporting the transmission shaft at each of axially-opposed sides of the radial air inlet. 
     
     
       19. The method as defined in  claim 16 , wherein driving the rotatable load includes driving an accessory gearbox of the engine with the transmission shaft. 
     
     
       20. The method as defined in  claim 19 , wherein driving the accessory gearbox includes driving a tower shaft of the engine with a drive shaft of the engine, and driving the transmission shaft with the tower shaft.