Theoretical studies of a continuously adjustable hydrodynamic fluid film bearing. The invention also has as an object a bearing permitting the relative rotation of a shaft and a casing comprising a plurality of sheets capable of generating a fluid film about the shaft, characterized by the fact that it comprises restraining means participating in the rigidity of the bearing while exerting forces on the sheets directed toward the shaft, the sheets participating in the stiffness of the bearing by an elastic repelling force directed toward the shaft.
The significance of the modification of the bearings properties achieved by active lubrication will be strongly dependent on the mass of the tiliting pad rotating system, if such a significance is evaluated using as criteria the damping factor or stability reserve of the rotor-bearing system.

21. The hydrostatic augmentation system of claim 20 wherein the compliant foil hydrodynamic fluid film journal bearing includes a cartridge having a plurality of axially extending peripheral slots and a plurality of radially extending end slots to promote cooling by the bleed air from the bearing rotor thrust disk.
The seat 18 is a radial recess provided on the inner surface 13 of the bearing housing 11 and has the shape of a parallelepiped having an opening on the inner surface 13, a plane base opposite to the opening and four plane lateral surfaces connecting the plane base to the opening.
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.

It was theoretically shown that it is possible to change the dynamic coefficients of multirecess journal bearings with a suitable choice of a PD controller, and in the plane rotor-bearing stability analysis, based on root locus method, it was shown that it is possible to increase the damping ratio of the under damped mode.
Moreover, Figure 6(a) shows one of the fluid frequencies crossing the first natural frequency of the rotor when the rotational speed is of approximately 53.6 Hz, what means to excite the first mode of the rotor at a rotational speed nearly twice the critical speed of the rotor.
22. The hydrostatic augmentation system of claim 20 wherein the compliant foil hydrodynamic fluid film journal bearing includes a cartridge having at least one generally arcuate axially extending cooling air cavity communicating with the interior of said cartridge.
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.

When the bearing rotor thrust disk 37 moves towards the turbine, more air bleeds outward and over the bearing rotor thrust disk 37 and around the turbine side thrust bearing and more air bleeds inward and between the compressor wheel back plane and thrust plate 42 causing the force exerted on the thrust disk surface to be somewhat diminished.