Squeeze film damper (SFD) is&nbsp;widely mounted&nbsp;on the rotor-bearing&nbsp;system for aero engine, and the&nbsp;damping performances of SFD are key factors to gain reliability and safety&nbsp;of the system.&nbsp;It is necessary to predict&nbsp;the effect&nbsp;of nonlinear&nbsp;oil film&nbsp;force of SFD on the steady-state and transient response&nbsp;characteristics of the complex coupled dual-rotor system.On the basis of&nbsp;the Timoshenko beam theory&nbsp;and the analytical expression of the nonlinear force for short SFD, a nonlinear multi-degree-of-freedom dynamic model of a coupled dual-rotor system with intershaft bearing and squeeze film damper is established by using finite element method. The critical speed characteristic diagram and vibration modes are obtained to analyze the natural&nbsp;characteristic&nbsp;of the coupled dual-rotor system.&nbsp;The results show that, within the working speed range, high-pressure rotor approximately exhibits rigid body mode, and the stiffness of the intershaft bearing has significant influenced on the first and third order critical speed of the system.Base on&nbsp;the developed nonlinear dynamic model,&nbsp;the steady-state&nbsp;unbalance&nbsp;response of the system is simulated&nbsp;with Newmark-β algorithm. The&nbsp;damping effect&nbsp;of SFD on the dynamic responses of the system are obtained&nbsp;as unbalanced excitation being in different&nbsp;locations. Moreover,&nbsp;the influences of the parameters of squeeze film&nbsp;damper on the steady-state response of the system is analyzed.Furthermore, at different rotating speeds, the transient responses induced by&nbsp;the&nbsp;sudden unbalance occurred in the fan of the system are numerical simulated, in which the sudden unbalanced excitation is described as a step function. To obtain the optimum designing parameters of SFD, the damping effect of the&nbsp;parameters of SFD on vibration&nbsp;responded to the sudden unbalance are examined.

Dynamic Analysis of a Coupled Dual-Rotor With Squeeze Film Damper Considering Sudden Unbalance

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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