The invention relates to a method of prolonging pitch bearing lifetime for a wind turbine as well as the pitch bearing itself. The method comprises the steps of: stopping the rotor (4) from rotating; removing a plurality of first fastening means used for mounting the blade (5) to the outer bearing ring (24); mounting a strengthening arc structure (10) on said outer bearing ring (24), opposite the blade (5); installing a plurality of second fastening means, thereby connecting said blade (5) and said strengthening arc structure (10) to said outer bearing ring (24).

A method for preventing a pitch bearing failure of a pitch system of a wind turbine includes monitoring, via at least one sensor, one or more electrical signals of a pitch motor of a pitch drive mechanism of the pitch system that drives a pitch bearing of the pitch system. The method also includes analyzing, via the controller, the one or more electrical signals of the pitch motor so as to remove noise and amplify outliers. Moreover, the method includes estimating bearing friction of the pitch bearing using the analyzed one or more electrical signals of the pitch motor. As such, the method includes implementing, via the controller, a control action when the estimated bearing friction of the pitch bearing indicates an anomaly in the pitch bearing.

A service life evaluation method and device for a pitch bearing of a wind turbine are provided. The method includes: acquiring a probability density of a pitch driving torque in M historical periods, wherein M is a positive integer; acquiring an angle cumulative value of a pitch angle in each of the M historical periods; determining an equivalent load of the pitch bearing based on the pitch driving torque, the probability density of the pitch driving torque in the M historical periods, and angle cumulative values in the M historical periods; and determining a consumed service life of the pitch bearing based on the equivalent load of the pitch bearing

The invention relates to a method of prolonging pitch bearing lifetime for a wind turbine as well as the pitch bearing itself. The method comprises the steps of: stopping the rotor (4) from rotating; removing a plurality of first fastening means used for mounting the blade (5) to the outer bearing ring (24); mounting a strengthening arc structure (10) on said outer bearing ring (24), opposite the blade (5); installing a plurality of second fastening means, thereby connecting said blade (5) and said strengthening arc structure (10) to said outer bearing ring (24).

A turbofan engine for an aircraft includes a fan and a fan actuation system. The fan has a plurality of fan blades coupled to a fan shaft having one or more fan bearings. The fan blades are rotatable about a pitch axis. The fan actuation system is disposed within a fan hub and includes one or more actuators for rotating the fan blades about the pitch axis and one or more radial thrust bearings. The fan actuation system is characterized by a fan actuation system length envelope in a range of 8.5 to 24 and given by

[00001]$\frac{N_{\mathrm{FB}}{D}_{\mathrm{FT}}}{L_{\mathrm{AXIAL}}\left(\frac{R_{\mathrm{TB}}}{N_{\mathrm{FB}}}\right)}.$

N.sub.FB is a number of the fan blades, D.sub.FT is a fan tip diameter of the fan blades, R.sub.TB is a thrust bearing radius of the radial thrust bearings, and L.sub.AXIAL is an axial length from a fan hub tip to the fan bearings.

The present disclosure relates to methods (100, 200) for lubricating a pitch bearing (72) connecting a blade (22) and a hub (20) of a wind turbine (10). A method (100) comprises determining (110) that lubricating the pitch bearing (72) is to be carried out; determining (120) a top limit for a thrust gradient, the thrust gradient being a derivative of thrust with respect to time; determining (130) a pitch rate for lubricating the pitch bearing (72) based at least partially on the top limit for the thrust gradient, and pitching (140) the wind turbine blade (22) at the determined pitch rate for lubricating the pitch bearing (72) such that the top limit for the thrust gradient is not exceeded.

(FIG. 3)

The present disclosure relates to a method (100) for operating a yaw system of a wind turbine (10), the yaw system comprising a yaw bearing (98), an annular gear (31) and a plurality of yaw drives (35) including a motor (33) with a motor brake (91), a gearbox (37) and a pinion (39) operatively connected with the motor (33). The method (100) comprises operating the plurality of yaw drives (35) to rotate a nacelle (16) with respect to a tower (15) of the wind turbine (10). The method further comprises stopping rotation of the nacelle (16) with respect to the tower (15), including closing the motor brakes (91) of the yaw drives (35). Furthermore, the method (100) comprises, after a waiting time, balancing loads experienced by the plurality of yaw drives (35) of the yaw system. The present disclosure also relates to a control system (92) for a wind turbine (10) that is configured to carry out such method (100).

A repair device is provided for a wind turbine having a bearing with damaged teeth driven by a motor. The repair device includes a carrier for connection to the bearing and radially aligned with the damaged teeth. A gear train is mounted on the carrier for creating a torque transfer path from the motor to non-damaged teeth of the bearing.

A wind turbine including a lower mount; a nacelle; a hub rotatably coupled to the nacelle and configured to rotate about a longitudinal axis of the hub; a generator housed within the nacelle and configured to convert kinetic energy of the hub to electricity; a plurality of pivotable blades coupled to the generator and configured to rotate with the hub, each pivotable blade of the plurality of pivotable blades configured to pivot about a longitudinal axis of the pivotable blade; and an annular shroud fixed to the lower mount and located radially outward of the plurality of pivotable blades, the annular shroud coupled to the nacelle by at least one support member that is inclined so as to extend frontward and radially outward from the nacelle to the annular shroud; wherein the lower mount is configured to passively rotate about a mast.

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 $\frac{N_{\mathrm{FB}}{D}_{\mathrm{FT}}{M}_{\mathrm{cruise}}}{\left(\frac{R_{\mathrm{TB}}}{N_{\mathrm{FB}}}\right)},$
where N.sub.FB is a number of the plurality of fan blades, D.sub.FT is a fan tip diameter of the plurality of fan blades, M.sub.cruise is a Mach number of the turbofan engine at cruise operating conditions, and R.sub.TB is a thrust bearing radius of the one or more thrust bearings.