Vibration Properties of Dual-Rotor Systems under Base Excitation, Mass Unbalance and Gravity

Liqiang Chen,Zhenkun Zeng,Jianjun Wang,Dayi Zhang

doi:10.3390/app12030960

Liqiang Chen, Zhenkun Zeng + Show 2 more

Open Access

https://doi.org/10.3390/app12030960

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Abstract

Rotor systems installed in a transportation system or under seismic excitations are considered to have a moving base. Although extensive research has been conducted on the dynamic behavior of the single-rotor system under base motions, few studies have dealt with the dynamics of dual-rotor systems, especially the counter-rotating dual-rotor systems used in airplane engines. Moreover, mass unbalance and gravity are unavoidable excitations for most rotor systems. Therefore, the vibration properties of a counter-rotating dual-rotor system with the coupled effects of base motions, mass unbalance and gravity are investigated in this paper for the first time. Using the Lagrange principle associated with the finite element method, a general model for dual-rotor systems under base motions was established by using Timoshenko beam elements, leading to a detailed analysis of the natural properties and harmonic responses of the system. The results revealed that different whirling modes (backward, forward or both) may be mutually excited. This research can be helpful for the design and vibration analysis of dual-rotor systems concerned with base motion.

Highlights

Rotating machines such as pumps, generators and ground gas turbines are fundamental equipment in the modern engineering applications
Base excitations should be concerned for a rotor system mounted on a transportation system or under seismic excitation
A counter-rotating dual-rotor system was selected as the research target for this paper

Summary

Introduction

Rotating machines such as pumps, generators and ground gas turbines are fundamental equipment in the modern engineering applications. Gravity and mass unbalance from center-of-mass eccentricity along the rotor axis are unavoidable excitation sources for analyzing these rotor system problems. Base excitations should be concerned for a rotor system mounted on a transportation system or under seismic excitation. These three excitations have mutual influences that induce intricate resonance problems. It is even more complicated for a counter-rotating dual-rotor system with inter-shaft bearings in airplane engines, compared with a single rotor system. It is important to reveal the vibration properties in detail for the dual-rotor system under base motions, mass unbalance and gravity

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