A Self-Acting Gas Journal Bearing with a Flexibly Supported Foil — Numerical Model of Bearing Dynamics

The work is devoted to an analysis of the journal bearing dynamics, while factors related to motion and friction of nonrotating elements of the sleeve are taken into account. Based on the originally established numerical model devoted to bearing static simulations, the thickness of gas film was determined as well as the pressure distribution in the bearing and its lift capacity. Moreover, the numerical program developed for dynamic simulations led to an analysis of forced vibrations of the system under consideration. It was possible to visualize a journal trajectory for the dynamic harmonic input function. The relationship between the frequency of excitation force and bearing stiffness has been identified numerically and compared with the experimental results. The Fast Fourier Transform (FFT) analysis of vibrations was implemented. In the spectrum, only a frequency of the input function was observed, whereas and a lack of subsynchronous frequencies pointed to the stable operation of the bearing. The established numerical model yields the basis for simulations carried out in order to determine correctly dynamic characteristics of an oil-free machine rotating system at the early stage of its design and during its operation.