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Handbook of Turbomachinery Second Edition Revised - Ventech!

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system weight and/or space requirements. There are generally quite severe<br />

temperature constraints on the placement <strong>of</strong> these bearings due to possible<br />

destruction <strong>of</strong> the properties <strong>of</strong> the magnetic material and electronic<br />

components. The improvement <strong>of</strong> these bearings is continuing at a rapid<br />

pace, and they are a highly desirable option for certain applications.<br />

Fluid-Film Dampers<br />

Fluid-film dampers (also called squeeze film dampers) have been successfully<br />

utilized for a relatively long time as a means <strong>of</strong> providing vibrational energy<br />

dissipation in rotating machinery. They are <strong>of</strong>ten used in conjunction with<br />

rolling element bearings that typically possess low damping characteristics.<br />

A fluid-film damper is similar to a fluid-film bearing except it is constructed<br />

so the relative angular velocity between the inner and outer surfaces <strong>of</strong> the<br />

damper are constrained to zero or at least to a low rate. A schematic <strong>of</strong> a<br />

series-connected rolling element bearing and a squeeze film damper is shown<br />

in Fig. 30. As the center <strong>of</strong> the rotating assembly moves laterally, the fluid in<br />

the damper is ‘‘squeezed,’’ providing a large velocity-dependent force. By<br />

Figure 30 Fluid-film damper schematic.<br />

Copyright © 2003 Marcel Dekker, Inc.

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