Session: 23-02 Gas Foil Bearings

Paper Number: 153670

Rotor Dynamic of Bearing-Rotor System Supported by Gas Foil Bearing Under Two Housing Excitations: Random Vibration and Transient Impulse 

As the core component of the onboard refrigeration system, the turbo cooler is used to expand and cool the hot bleed of the engine, thus providing cold air. The extremely high rotating speed of the turbo cooler places significant demands on the reliability of the bearing. Gas foil bearing, as an oil-free bearing, is one of the best choices for turbo cooler due to the low friction loss and high stability. The turbo cooler experiences random vibration during operation, which can greatly affect the dynamic stability of the bearing-rotor system. It is crucial for the widespread onboard applications of gas foil bearing to adapt to the random vibration, maintain the stability of the bearing-rotor system, and prevent rotor instability or resonance. This paper focuses on the assessment and validation of the prediction method for the nonlinear dynamic characteristics of the bearing-rotor system in the turbo cooler supported by gas foil bearing.

In this paper, a dynamic model of the turbo cooler bearing-rotor system was developed based on the finite element method (FEM). The elastic shaft section was constructed using Timoshenko beam units, and treating the impeller and thrust disc as rigid concentrated mass points. A mathematical characterization model was also established to describe the random vibration under the operating conditions of the turbo cooler according to the random acceleration power spectrum density (PSD) from 10 Hz to 2000 Hz specified by the relevant vibration test. The nonlinear vibration characteristics of the bearing-rotor system of the turbo cooler under random vibration were studied. Additionally, the influences of foil stiffness and clearance of the gas foil bearing on the dynamic stability of the bearing-rotor system were compared and analyzed.

The prediction results indicate that the present method can approximately describe the random vibration experienced by the turbo cooler under actual operating conditions. Random vibration can significantly affect the dynamic stability of the bearing-rotor system. Therefore, it is necessary to select appropriate foil stiffness and clearance of the gas foil bearing to enhance the dynamic stability of the turbo cooler.

Presenting Author: Dake Sun Xi'an Jiaotong University

Presenting Author Biography: Dake Sun is a Ph. D student in the Institute of Turbomachinery at Xi’an jiaotong University. His research interests are in gas bearing technique and nonlinear rotordynamics of turbomachinery.

Authors:

Dake Sun Xi'an Jiaotong University
Zhuocong Li Xi'an Jiaotong University
Zhigang Li Xi'an Jiaotong University
Jun Li Xi'an Jiaotong University