A wind turbine generator system and a rotation speed avoidance control method therefor. The method comprises: according to statistical information of the rotation speed of a generator being in a rotation speed avoidance interval, identifying whether a wind turbine generator system repeatedly falls within the rotation speed avoidance interval; and when it is determined that the wind turbine generator system repeatedly falls within the rotation speed avoidance interval, adjusting a rotation speed avoidance control parameter of the wind turbine generator system according to the statistical information of the rotation speed being in the rotation speed avoidance interval. Correspondingly, further provided is a rotation speed avoidance control apparatus for a wind turbine generator system.

Methods and Apparatuses for rotational speed avoidance control of a wind turbine, and the wind turbine are provided. An exemplary method includes: identifying whether a wind turbine operates repeatedly traversing a rotational speed avoidance range, based on statistical information about a rotational speed of a generator being in the rotational speed avoidance range; and adjusting a parameter of a pitch control system and/or a parameter of an electromagnetic torque control of the wind turbine based on the statistical information about the rotational speed being in the rotational speed avoidance range, in response to determining that the wind turbine operates repeatedly traversing the rotational speed avoidance range.

A method for operating a wind turbine with hinged wind turbine blades is disclosed. The wind turbine comprises an adjustable biasing mechanism arranged to apply an adjustable biasing force to each wind turbine blade which biases the wind turbine blade towards a position defining a minimum pivot angle or towards a position defining maximum pivot angle. A biasing force is selected for each wind turbine blade and the selected biasing force is applied to the respective wind turbine blades. The wind turbine is operated while monitoring rotor unbalance of the wind turbine. In the case that the rotor unbalance exceeds a first threshold value at least one of the wind turbine blades is selected, and the biasing force applied to the selected wind turbine blade(s) is adjusted.

Provided are a vacuum pump, a magnetic bearing device, and a rotor that suppress swinging and vibration of a rotor. A vacuum pump includes, in the following order in the exhaust direction of a gas, the center of gravity of a rotor, an active radial bearing that supports the rotor in the radial direction in a non-contact manner by using a magnetic force, and a passive radial bearing that supports the rotor in the radial direction in a non-contact manner using a magnetic force.

There is provided a method of avoiding edgewise vibrations during a non-operational period of a wind turbine. The method comprises defining a non-operational period for a wind turbine arranged at a specific site, determining expected wind conditions at the specific site during the non-operational period and defining a plurality of potential yaw orientations for the wind turbine. The method further comprises determining the relative probability of edgewise vibrations occurring during the non-operational period for each potential yaw orientation based upon the expected wind conditions during the non-operational period, determining one or more preferred yaw orientations, which are the yaw orientations in which the probability of edgewise vibrations occurring is lowest, and arranging the wind turbine in one of the preferred yaw orientations during the non-operational period.

A gas turbine engine includes combustion apparatus defining a volume, a compressor, a cooling air supply feed from the compressor, and a Helmholtz resonator. The Helmholtz resonator has a neck and a chamber having an attenuation volume and which is in fluid communication with the attenuation volume, the cooling air supply feed is connected to the Helmholtz resonator and includes a valve arrangement. In a first engine operating condition, the valve arrangement is closed and the Helmholtz resonator attenuates acoustic frequencies in a first range and, in a second engine operating condition, the valve arrangement is open whereby cooling air purges the attenuation volume and the Helmholtz resonator attenuates acoustic frequencies in a second range.

A compressor includes a case, a compression unit having a cylinder, a piston disposed inside the cylinder, and a driving unit for reciprocating the piston, and a support unit elastically supporting the compression unit to be spaced apart from an inner surface of the case. The support unit includes a wire spring having a plurality of linear portions arranged in parallel with one another and curved portions each connecting two adjacent linear portions. The wire spring includes a first wire spring and a second wire spring symmetrically disposed with each other. The wire spring includes a connecting portion connecting the first wire spring and the second wire spring, and the connecting portion is supported by the case. Accordingly, a simplified structure can be obtained and a manufacturing cost can be reduced.

An acoustic core may include an array of resonant cells configured as a plurality of resonant cell groups. The resonant cell groups may include a plurality of resonant cells configured as a partitioned resonant cell that include a converging resonant cell and a diverging resonant cell. The converging resonant cell and the diverging resonant cell may be defined by a plurality of cell walls integrally formed with one another and a partition integrally formed with the plurality of cell walls. The partition may at least partially delimit the converging resonant cell from the diverging resonant cell. The converging resonant cell may define an upper resonant space delimited by the partition and a top face of the array of resonant cells. The diverging resonant cell may define a lower resonant space delimited by the partition and a bottom face of the array of resonant cells.

Blades (20a to 20c) of a propeller fan (10) have different circumferential pitches φ1, φ2, and φ3. The blades (20a to 20c) have different masses so that the center of gravity of the propeller fan (10) is positioned on a rotational center axis (11) of the propeller fan (10). Blade body portions (42c) of the blades (20a to 20c) have different thicknesses. In contrast, camber lines of the blades (20a to 20c) in blade cross section have the same shape, projections of the blades (20a to 20c) on a plane perpendicular to the rotational center axis (11) of the propeller fan (10) have the same shape, and leading edge portions (41a to 41c) of the blades (20a to 20c) have the same shape. As a result, a propeller fan (10) having reduced noise and vibrations can be achieved.

An enclosure with a vortex-induced vibration suppression function and a method for suppressing vortex-induced vibration are provided. The enclosure is provided with suction through holes extending through a peripheral wall thereof, the suction through holes are distributed in a circumferential direction of the enclosure. The enclosure is further provided with a suction apparatus, and the suction apparatus can perform suctioning to the suction through holes from outside to inside, to restrain a boundary layer at an outer surface of the enclosure from being detached from the outer surface. By the suctioning, the boundary layer can be “adsorbed” on the outer surface of the tower, thereby restraining or directly preventing the boundary layer from being detached from the outer surface of the tower, and reducing or eliminating the cause of the vertex-induced vibration.