Turbofan engine including a fan actuation system
A turbofan engine includes a fan and a fan actuation system. The fan has a plurality of fan blades. Each of the plurality of fan blades is rotatable about a pitch axis. The fan actuation system includes one or more actuators for rotating the plurality of fan blades about the pitch axis and one or more thrust bearings. The fan actuation system is characterized by a fan actuation system envelope in a range of 300 to 1860. The fan actuation system envelope is given by N FB × D FT × M cruise ( R TB N FB ) , where N FB is a number of the plurality of fan blades, D FT is a fan tip diameter of the plurality of fan blades, M cruise is a Mach number of the turbofan engine at cruise operating conditions, and R TB is a thrust bearing radius of the one or more thrust bearings.
1. A turbofan engine comprising:
a fan having a plurality of fan blades, the fan being an open fan, and each of the plurality of fan blades being rotatable about a pitch axis; and
a fan actuation system including one or more actuators for rotating the plurality of fan blades about the pitch axis and one or more thrust bearings, wherein the fan actuation system is characterized by a fan actuation system envelope in a range of 660 to 1860, the fan actuation system envelope being given by:
N
FB
×
D
FT
×
M
cruise
(
R
TB
N
FB
)
wherein N FB is a number of the plurality of fan blades, D FT is a fan tip diameter of the plurality of fan blades in a range of 120.0 inches to 168.0 inches, M cruise is a Mach number of the turbofan engine at cruise operating conditions, and R TB is a thrust bearing radius of the one or more thrust bearings in a range of 20 inches to 27 inches.
2. The turbofan engine of claim 1 , wherein the fan actuation system includes a hydraulic system that supplies hydraulic fluid for rotating the plurality of fan blades about the pitch axis.
3. The turbofan engine of claim 1 , wherein N FB is in a range of ten to fourteen.
4. The turbofan engine of claim 1 , wherein M cruise is in a range of 0.7 to 0.9.
5. The turbofan engine of claim 4 , wherein M cruise is in a range of 0.75 to 0.9.
6. The turbofan engine of claim 4 , wherein M cruise is in a range of 0.8 to 0.88.
7. The turbofan engine of claim 1 , wherein the fan actuation system includes a pressurized pneumatic chamber that is filled with a pressurized gas that biases the plurality of fan blades to a feather position.
8. The turbofan engine of claim 7 , wherein the fan actuation system is devoid of counterweights for reducing inertial loading associated with rotation of the plurality of fan blades.
9. The turbofan engine of claim 1 , further comprising a turbo-engine having a core inlet, wherein the turbofan engine has a longitudinal centerline axis, and the core inlet is annular about the longitudinal centerline axis.
10. The turbofan engine of claim 9 , further comprising a gearbox assembly, wherein the turbo-engine includes a low-pressure shaft, and the fan has a fan shaft that is coupled to the low-pressure shaft through the gearbox assembly.
11. The turbofan engine of claim 10 , wherein the gearbox assembly has a gear ratio in a range of 4:1 and 12:1 for an unducted fan engine.
12. The turbofan engine of claim 10 , wherein the low-pressure shaft, the gearbox assembly, and the fan shaft are coaxial along the longitudinal centerline axis.
13. The turbofan engine of claim 10 , wherein the turbo-engine further includes a high-pressure shaft, the low-pressure shaft being disposed through the high-pressure shaft.
14. The turbofan engine of claim 1 , wherein the fan actuation system is devoid of a pitch lock device for locking a pitch of the plurality of fan blades.
15. The turbofan engine of claim 1 , wherein the fan actuation system includes a trunnion mechanism having a plurality of trunnions, the plurality of fan blades extending from a disk and being disposed within the plurality of trunnions.
16. The turbofan engine of claim 15 , wherein the one or more thrust bearings are disposed between the plurality of trunnions and the disk such that the plurality of trunnions rotates with respect to the disk to rotate the plurality of fan blades about the pitch axis.
17. A turbofan engine comprising:
a fan having a plurality of fan blades coupled to a fan shaft, the fan being an open fan, and each of the plurality of fan blades being rotatable about a pitch axis;
a turbo-engine having a core inlet and including a low-pressure shaft, wherein the turbofan engine has a longitudinal centerline axis, and the core inlet is annular about the longitudinal centerline axis;
a gearbox assembly, the fan shaft that being coupled to the low-pressure shaft through the gearbox assembly, wherein the low-pressure shaft, the gearbox assembly, and the fan shaft are coaxial along the longitudinal centerline axis; and
a fan actuation system including one or more actuators for rotating the plurality of fan blades about the pitch axis and one or more thrust bearings, wherein the fan actuation system is characterized by a fan actuation system envelope in a range of 660 to 1860, the fan actuation system envelope being given by:
N
F
B
×
D
F
T
×
M
cruise
(
R
T
B
N
F
B
)
wherein N FB is a number of the plurality of fan blades in a range of ten to fourteen, D FT is a fan tip diameter of the plurality of fan blades in a range of 120.0 inches to 168.0 inches, M cruise is a Mach number of the turbofan engine at cruise operating conditions, and R TB is a thrust bearing radius of the one or more thrust bearings in a range of 20 inches to 27 inches.
18. The turbofan engine of claim 17 , wherein the fan actuation system includes a hydraulic system that supplies hydraulic fluid for rotating the plurality of fan blades about the pitch axis.
19. The turbofan engine of claim 17 , wherein M cruise is in a range of 0.7 to 0.9.
20. The turbofan engine of claim 17 , wherein the fan actuation system includes a pressurized pneumatic chamber that is filled with a pressurized gas that biases the plurality of fan blades to a feather position.