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Handbook of Turbomachinery Second Edition Revised - Ventech!

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INTRODUCTION<br />

10<br />

Rotordynamic Considerations<br />

Harold D. Nelson<br />

Arizona State University, Tempe, Arizona, U.S.A.<br />

Paul B. Talbert<br />

Honeywell Engines, Systems and Services, Phoenix, Arizona, U.S.A.<br />

The discipline <strong>of</strong> rotordynamics is concerned with the free and forced<br />

response <strong>of</strong> structural systems that contain high-speed rotating assemblies.<br />

The concern here is with the dynamic characteristics <strong>of</strong> systems with rotor<br />

assemblies that spin nominally about their longitudinal axes. Examples <strong>of</strong><br />

such systems, Fig. 1, include gas turbines, steam turbines, pumps,<br />

compressors, turbochargers, electric motors and generators, etc. A<br />

completely separate area <strong>of</strong> rotordynamics, not addressed here, is concerned<br />

with structural systems with rotor assemblies that spin nominally about an<br />

axis perpendicular to the axis <strong>of</strong> the rotor such as encountered with<br />

helicopter blades or propellers. The interest here focuses primarily on the<br />

displacement components (both translation and bending rotation) and<br />

associated forces and moments that are linked with motion <strong>of</strong> a shaft<br />

perpendicular to the shaft centerline.<br />

Vibration problems that exist in rotordynamic systems are caused by a<br />

variety <strong>of</strong> different excitation sources. Residual rotating unbalance and selfexcitation<br />

mechanisms are two <strong>of</strong> the more prevalent. The rotating unbalance<br />

Copyright © 2003 Marcel Dekker, Inc.

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