S iv ACKNOWLWDGEMENTS vi TABLE OF CONTENTS viii LIST OF TABLES xii LIST OF FIGURES xvii NOMENCLATURE xx CHAPTER 1: INTRODUCTION 1 1.1. General Background 1 1.2. Lubrication of the Components of Aeronautical Power Systems 4 1.3 The Scope of the Present Work 6 CHAPTER 2: CURRENT RESEARCH IN SQUEEZE FILM DAMPERS 8 2.

Numerical predictions and measurements in the lubrication of aeronautical engine and transmission components

Multiple-objective design optimization of squirrel cage for squeeze film damper by using cell mapping method and experimental validation

This paper investigates the unbalance response of a squeeze film damper-mounted flexible rotor. Both concentric and eccentric damper operations are examined. Comparison between predicted and experimental results shows that the '0' film model is preferred to the 'π' film model. Near the first pin-pin critical speed the '0' film model underestimates the damping effect and overestimates the centralizing force of the damper. By choosing a lower film rupture pressure in the theoretical model, better matches to the experimental results are obtained. The effects of air entrainment are shown to produce unsteady responses and jump phenomena of softening spring type. It is concluded that damper models having constant film rupture pressures do not truly represent the cavitation problem in squeeze film dampers.

Unbalance Response of a Flexible Rotor Supported by a Squeeze Film Damper

Experimental and numerical investigation on the performance of fluid pivot journal bearing in one-sided floating state

Transient Response of a Short-Length (L/D = 0.2) Open-Ends Elastically Supported Squeeze Film Damper: Centered and Largely Off-Centered Whirl Motions

The ability of an uncentralized squeeze-film damper bearing to inhibit the effects of vibration in a flexible rotor-bearing system, has been assessed in terms of non-dimensional system parameters. This analytical approach has shown that a correctly designed squeeze-film damper bearing is a very effective means of reducing both the amplitude of motion of the rotor and the force transmitted to the bearing support structure. However, the analysis has also indicated that a poorly designed squeeze-film damper bearing can produce amplitudes and forces greater than those which would arise if the bearing support remained rigid. An experimental programme has supported the validity of the above analytical technique by showing that the measured motion orbits of the journal and disk centers as the rotor passes through the critical speed, are very similar to those predicted theoretically. Also, the response curves for specific groups of system parameters show very similar trends in practice, to those which result from the analytical approach. Some indication of the ability of a squeeze-film damper bearing to reduce the effect of much greater unbalance than normal is also reported.

S. S. Kossa

Papers

The Vibration Isolating Properties of Uncentralized Squeeze-Film Damper Bearings Supporting a Flexible Rotor