Analysis of rotor motion trajectories on a leaf-type bearing.
Keywords:
leaf-type bearing, gas bearing, gas lubricant, experiment, rotor dynamics, spectral analysis, rotor orbitAbstract
Increasing demands for the reliability and efficiency of high-speed rotor systems used in turbomachinery, aircraft engines, and power engineering equipment are directly related to the processes occurring in gas-supported bearings. In this regard, foil gas dynamic bearings represent a promising alternative to conventional oil-lubricated supports due to the absence of lubrication, low friction losses, and the ability to operate under extreme temperature conditions. Despite these advantages, the nonlinear nature of the gas film and the complex dynamics of rotor interaction with the deformable foil structure create significant difficulties in predicting rotor trajectories, which may lead to instability and resonance phenomena. The aim of this study is to analyze rotor motion trajectories in foil gas dynamic bearings at different rotational speeds. To determine the stiffness of the elastic foil package, a combined approach was implemented. Numerical simulation of unsteady gas lubrication processes was performed in ANSYS using a model of elastic foil deformation. In parallel with the numerical analysis, a series of experiments was carried out on a dedicated test rig. Two mutually perpendicular proximity probes were used to reconstruct rotor orbits and perform spectral analysis of the measured signals. Experimental data processing included decomposition of the signals into harmonic components followed by comparison of frequency components and reconstruction of motion trajectories. The main result of the study is a comparison of orbit amplitudes obtained numerically and experimentally. It was established that the relative deviation of amplitudes does not exceed 7 %, while the main frequencies and dominant harmonics fully coincide. The obtained results confirm the adequacy of the developed model and demonstrate the possibility of its application for analyzing the dynamics of foil gas dynamic bearings, evaluating rotor system stability, and predicting vibration operating conditions of high-speed rotating equipment.References
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