| Squeeze Film Bearing Dampers are passive machine elements incorporated into rotating machinery, normally between rotor and housing, at the bearing locations. The dampers reduce forces and vibrations transferred between rotor and housing, and may stabilize an otherwise unstable rotor system. Proper choices of the design parameters are critical for a successful implementation. Aircraft and automotive gas turbines, centrifugal compressors and pumps are typical examples of machinery incorporating squeeze film bearing dampers.; Following a tutorial treatment, the present work treats the following aspects of squeeze film bearing dampers intended for rigid rotors: (1) Analysis, in which theoretical relationships between design parameters and performance characteristics are developed, design criteria are discussed, and design charts for steady-state operation with, or without retaining springs of various stiffnesses, are provided. Analytical expressions for parameter values bounding bistable operating regimes are given, and ranges of inadmissible eccentricities are established. (2) Dynamic simulation for the study of transient dynamics, in which nonlinear models and computer simulation programs are first developed for a single squeeze film bearing damper, and subsequently formulated for a system consisting of a rigid rotor supported by squeeze film bearing dampers at both ends. The latter model permits journal and bearing axes which are skew relative to each other. (3) Experiments, in which qualitative characteristics of operation under atmospheric or very low pressure under various rotor imbalance conditions are investigated, and the effectiveness of the squeeze film bearing damper in attenuating ball bearing vibrations is evaluated by comparison to a rotor system without dampers; (4) Design, in which an outline for a design procedure is given, important design parameters are discussed, and design concepts are presented.; Comprehensive analytical developments of both kinematics and dynamics of a rigid rotor, cast in the form of Kane's dynamical equations, as well as a coherent treatment of the fluid dynamics of the squeeze film bearing damper from first principles, are included in the appendixes. A detailed description of the test rig, featuring absolute isolation from drive train vibrations, is furnished, and measurement correction algorithms are discussed. A comprehensive bibliographic reference section is included. |
