Research On Influences Of Supporting On Dynamic Characteristics Of The Dual-rotor System

With the improvement of aircraft engine’s performance, the dual-rotor system has been more andmore used in aircraft engine. As an important part in the system, the impact of supporting of dual rotorsystem on dynamic characteristics of the dual rotor has great research value. In this paper, thesupporting’s own characteristics and its impact on dynamic characteristics of the dual rotor systemwere studied with simulation and experiments. The main works are as follows:1) With the foundation of Reynolds equation, combined with the whole flow theory, derivation ofthe steady Reynolds equations for inner and outer layers of the floating-ring squeeze filmdampers (FSFD), the impact of structural parameters such as eccentric distance, oil filmthickness, clearance et al on the vibration reduction characteristics was calculated and verifiedwith experiment. The results showed that the pressures of inner and outer oil films increasedalong with the increase of the eccentricity ratio and the oil film width, and they decreased alongwith the increase of oil film clearance. Big eccentricity ratio and small clearance brought strongnonlinearity to the FSFD. The conclusions provided theoretical guidance to the design ofpractical support damping structure.2) The finite element model of support-dual rotor system was established. The impact of supportsimplification method on critical speed was studied. It was shown that in three models, themaximal critical speeds came from model with dynamic stiffness from test, results from modelwith static stiffness took the second place, and the minimum results came from model withsimulated dynamic stiffness. The support damping reduced vibration significantly and led toslightly increase of first three critical speeds.3) The transfer matrix method was adopted to calculate dynamic characteristics of dual rotor systemwith different support stiffness, speed ratios and amount of supporting. The results showed thatthe linearity changed greatly within certain range of parameters. So it was suggested this rangeshould be avoided when determining the supporting plan. The dynamic characteristics andcomplexity of4-support plan and5-support plan has been analyzed. The conclusions providedreferences for the engineering practice.4) Experiments were carried out to study the dynamic characteristics of dual rotor system. Theresults of the finite element method and the transfer matrix method were verified with theexperiments. It was shown that the dual rotor system with dynamic stiffness from test was theclosest to the practical working condition. The impact of speed ratio was verified for dynamic characteristics of the dual rotor system.