Research On The Dynamics Of Rotor Support System In Marine Gas Turbine

Due to operation demands, working speed of modern marine gas turbine often above thecritical speed of the rotor system’s rigid mode or even of the bending mode, that make excessivedemands on vibration control of rotor system, because rotor and supporting system produce alarge vibration when the rotor speed approach or or pass through the critical speed. At present,the most widely used combined supporting in the engine is elastic supporting and squeeze filmdamper structure, because it has outstanding advantages of obvious vibration-isolating effect,simple structure, high reliability, and the ability of frequency control. So according to the actualsituation the research about combined squirrel cage elastic supporting and squeeze film damperhas important practical significance. In this thesis, the stiffness and damping characteristics ofthe elastic supporting and squeeze film damper were analyzed with theory and test, and studiedits effect on the dynamic characteristics of rotor systems.First of all, the stiffness characteristics of squirrel cage elastic supporting are calculatedusing calculation formula and finite element method, and the basic change rules of stiffness ofsquirrel cage with structural parameters are gotten via experimental study, and the effect whichimpact the error of the squirrel cage stiffness were obtained. Meanwhile, the accuracy of finiteelement analysis is identified, a revised parameterization calculation formula are obtained.Moreover, Reynolds equation of squeeze film damper were derived, oil-film force modeland its dynamic parameters of the formula based on the assumption of short bearing wereestablished, and combined with the damping characteristics tested by adopting pulse excitationmethod, the basic change rules of the damping characteristics of squeeze film damper withstructural parameters are obtained, the damping characteristics of squeeze film damper areresearched.Finally, based on the previous study, the calculation procedure of squeeze film damper oilfilm force model is developed, a dynamic model of squirrel elastic supporting-squeeze filmdamper-bearing-rotor system is established, the dynamic characteristics of rotor-supportingsystem are calculated by using Newmark numerical solution; the rule of elastic supporting tochange the rotor system critical speed laws and the damping mechnaism of squeeze film damperto the rotor system are achieved. And based on experimental test, the influence law of thedamper radius gap and unbalance to the dynamic characteristics of squirrel cage elastic supporting–squeeze film damper–rotor system is studied.