Anisotropic support damper for gas turbine bearing

#The present invention generally relates to a turbo machinery and, more specifically, to a system and apparatus that interfaces between bearing elements and the static support structure for turbo machinery.

#Synchronous vibration caused by mass imbalance is common in rotating machinery and is usually caused by a rotating mass inbalance. Imbalance frequently occurs when the mass center of the rotor is not coincident with its geometric center. Another form of vibration is non-synchronous rotor whirl, which occurs when a radial deflection of the rotor results in tangential force normal to the deflection. The magnitude of the tangential force increases with the deflection. The system will become unstable if there is insufficient damping. Damping the vibration in a turbomachine provides quiet and comfortable efficient operation of the machine, reduced fatigue stress on the machine and its supports, and a safeguard to the damage that can be caused by unstable vibration.

#Generally, within rotating machinery, at least two bearings are required to support the rotating shaft, and these bearings must accommodate misalignments between the bearing and the rotor. Misalignments can cause some bearings to bear an excessive load, while other bearing are carrying very little load. Various solutions have been attempted to reduce misalignment, limit maneuver deflection and reduce vibration.

#These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

#FIG. 1 is a cross sectional view of the present invention according to one embodiment; and

#FIG. 2 is an isometric view of the present invention according to the same embodiment.

#The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

#The present invention provides a centering feature to the bearing of turbo machinery, eliminating unstable vibrations and improving synchronous vibrations. It is unlike the prior art in that asymmetrically arranged beams achieve flexibility and bearing support anisotropy, the bearing support accommodates open, closed or re-circulating squeeze film damper in parallel. The bearing support may also be the bearing outer race, resulting in improved internal rolling element clearance for better dynamic behavior, and the bearing support limits maneuver and blade loss by limiting rotor exclusion.

#One aspect of the invention is an apparatus for supporting and stabilizing a rotating shaft in a machine comprising a rotor group supported by at least two bearing assemblies, a support housing surrounding the bearing assemblies and connected to an engine case. The bearing assembly may be stacked with a stub shaft and clamped by a nut. It should be understood that the bearing assembly may contain any bearing known within the art. According to one embodiment, the bearing may be a roller bearing. The support housing may have a non-concentric bore, which centers the rotor when support is statically deflected by the weight of the rotor. The support housing accommodates at least one anisotropic support damper comprised of at least two rings connected by asymmetrically arranged beams, wherein the anisotropic damper may be removably attached to said support housing and interface the bearing assemblies and support housing. The cross-section, length and number of said asymmetrically arranged beams are chosen as to provide stabilizing cross-coupling stiffness. The anisotropic damper may be hydraulically mounted open, closed or re-circulating.