In this study, the effect of misalignments
on the instability thresholds of a shaft-bearing system
supported by two externally pressurized air journal
bearings is investigated. Semi-implicit method is used to
reduce computing time for unsteady Reynolds’ equation.
The fourth order Runge-Kutta method is applied for
solving the equation of motions. In addition, FFT
processing is used for analyzing half-frequency whirl
phenomena and calculating threshold speed. In this study,
a technique is used for calculating non-tridiagonal
matrices that have periodic boundary conditions. Results
show that the effect of misalignment of journal bearings
on the instability is quite significant.