Fluid Bearing

Another form of lubrication is the 'elastohydrodynamic' lubrication. While the backing will invariably be steel, a steel bearing running against a steel journal with no coating on either surface would cause high friction and wear in the boundary and mixed lubrication modes, and would provide little or no ability to allow foreign particles to embed in the material, but would instead capture them and turn them into cutting tools.
For good operation of the bearing, it is imperative that the fluid film between the sheets and the shaft never be destroyed, in particular by unbalance of the bearing, by the weight of the shaft, fluid film bearing by vibrations, by acceleration and by the gyroscopic effects resulting from the rotation of the shaft or of the casing and the displacement of the bearing, for example rising in an aircraft.

Compared with classic application of fluid film bearings such gas and steam turbines, cement mills, ship propulsion and others, the loadings in wind turbine has a high dynamic characteristic, i.e. the loading acting on the bearing has a great variability.
Also, the hydrostatically generated thrust forces will be a function of the axial position of the bearing rotor thrust disk 37. The flow of bleed air through the compliant foil hydrodynamic fluid film thrust bearing will be affected by the axial position of the bearing rotor thrust disk 37 and this relative position will serve as a variable orifice flow control of the bleed air used to attenuate the hydrostatically generated thrust forces.
Another design option that significantly affects bearing performance is the method of introducing lubricant into the bearing and removing it. By supplying lubricant to the leading edge of the tilt pad and allowing the lubricant to freely exit the bearing and its housing, directed lubrication bearings operate with lower power losses and at lower operating temperatures than flooded bearings, where the lubricant is typically fed into the bearing away from the film and flow out of the bearing is restricted.

The release of RBTS' ARMD Version 6 fluid-film bearing modules is a major milestone in the product's development history, rolling out a completely new and improved graphical user interface for the package with enhanced numerical capabilities and new technical features.
Figure 7: Natural modes of configuration A for a rotational speed of 40 Hz: (a) bearing 2 fluid frequency at 21.83 Hz; (b) bearing 1 fluid frequency at 20.85 Hz; (c) first forward flexural natural frequency at 25.74 Hz; (d) first backward flexural natural frequency at 27.01 Hz.
Orifice means in said fluid foil member of said compressor side bilateral compliant foil hydrodynamic fluid film thrust bearing to deliver bleed air against the bearing rotor thrust disk to augment the thrust force applied by the hydrodynamic thrust bearing to the compressor side of said bearing rotor thrust disk.
7. The hydrostatic augmentation system of claim 1 wherein said bilateral compliant foil hydrodynamic fluid film thrust bearing includes a thrust plate on the compressor side thereof, and said means to deliver bleed air to the compressor side of said bilateral compliant foil hydrodynamic fluid film thrust bearing includes a plurality of enlarged recesses on the bearing rotor thrust disk side of said thrust plate.

In the present invention, the unequal loading of the opposite sides of a bilateral compliant foil hydrodynamic fluid film thrust bearing is reduced or eliminated by hydrostatically augmenting one side of the bilateral compliant foil hydrodynamic fluid film thrust bearing with bleed air from the compressor which is rotatably supported by the bilateral compliant foil hydrodynamic fluid film thrust bearing and compliant foil hydrodynamic fluid film journal bearings.