Session: 27-05 Non-Linear Rotordynamics

Paper Number: 125492

125492 - Dynamic Prediction of Elastic-Supported Rotor With Friction Damper Based on 3D Contact Model 

The vibration suppression of turbomachinery rotors through the elastic support equipped with dry friction damping is receiving increasing attention. Combined with actuators that can adjust the normal force on the frictional interface, this damping strategy has a promising prospect to achieve the vibration reduction of rotors under variable operating conditions. By using a high-fidelity finite element model in the dynamic analysis, one can not only obtain more accurate quantitative response of the rotor, but also can capture the distribution of contact state on the frictional interface, which will help to optimize the dry friction damping structure. Nevertheless, the distributed local strong nonlinearity brought by the frictional hysteresis on the discretized contact interface yields difficulties for predicting the dynamic behaviors of the rotor-elastic support system.

In this work, we propose a harmonic balance-based method for predicting the unbalanced response of the elastic supported rotor damped by a frictional damping structure. Distributed full-3D contact models are used to describe the nonlinear constitutive relationship of the contact interface. Thus, both the time-varying normal force induced by the coupling of normal/tangential vibration and the curvilinear in-plane relative motion trajectory driven by the rotor whirl can be captured. To reduce the size of the large-scaled finite element model of the rotor-support system, a multi-step ROM technique is adopted, including the Craig-Bampton sub-structural method, the dynamic condensation, and the transformation to the relative displacements of contact pairs. The corresponding analytical Jacobian matrix is derived to enhance the computational efficiency and convergence.

To validate the accuracy of the proposed method, the Newmark-β integration is used as a reference. Results show that the relative error of the response amplitude is less than 4% based on a 60-DOF simplified rotor-support model equipped with a friction damper. Then, we apply this method to the high-fidelity finite element model of a frictionally damped rotor system. The elastic support with dry friction damping is designed in the form of an elastic ring. There are totally 85357 DOFs of the entire finite element model including 24 nonlinear DOFs on the frictional interface. After model reduction, only 12 DOFs are retained, and the average simulation time is only 0.59 seconds for each frequency point. Finally, we carry out parameter studies to clarify how the normal force, excitation level, friction coefficient, contact stiffness, rotor orbit, and the position of elastic support/dry friction damper affect the vibration suppression performance.

The in-house code developed in this study calculates accurately and efficiently the unbalanced response of large-scaled rotor systems with elastic support/dry friction dampers. Furthermore, it offers a precise depiction of contact state distribution on the interface and the motion trajectory of friction pairs.

Presenting Author: Shengshuo Wang Beihang Univ

Presenting Author Biography: Shengshuo WANG is Ph.D. candidate in School of Energy and Power Engineering of Beihang University. His research interests are rotor dynamics and dry friction damping.

Authors:

Yu Fan Beihang Univ
Shengshuo Wang Beihang Univ
Yaguang WU Beihang University
Shanzi Zhang Shanghai Electric Gas Turbine, Co., Ltd.
Yiwen Shen Shanghai Electric Gas Turbine, Co., Ltd.
Mingmin Chen Shanghai Electric Gas Turbine, Co., Ltd.