Dynamic characteristics of flexible rotor with squeeze film damper excited by two frequencies

Abstract

This paper is focused on the dynamic characteristics of a flexible rotor with squeeze film damper excited by two frequencies. The multiple harmonic balance method and Runge–Kutta method are combined to analyze the periodic solution and quasi-periodic solution of the system. The nonlinear characteristics discussed are fastened on the resonance region corresponding, respectively, to the rigid body translation mode and first bending mode. In the former region, the motion of disk center shows the ‘hard spring’ characteristic, and the combination frequencies are dominated by the difference between double low excitation frequency and high excitation frequency and the difference between double high excitation frequency and low excitation frequency. In the latter region, however, the combination frequencies are dominated by the difference between high excitation frequency and double low excitation frequency and the difference between triple low excitation frequency and double high excitation frequency. Moreover, the motion of disk center shows a kind of ‘cross’, ‘soft spring’ or ‘hard spring’ characteristics with the variation of the ratio of the two excitation frequencies. Besides, the independent quasi-periodic solution coexists with the periodic solution in these cases. The system is sensitive to the ratio of excitation frequencies, and it could have two independent quasi-periodic solutions in some conditions. The results in this paper provide a reveal of nonlinear characteristics in this type of double excitation nonlinear rotor system.