Unstable tilting motion of flexibly supported gas bearing bushings

This paper presents measurements of the motion amplitudes from flexibly supported Herringbone Grooved Journal Bearing bushings. Measurements taken in four locations on bearing bushing enable distinction between radial and tilting motion, which allowed to identify an unstable mode. The instability can be attributed cross-coupled impedance gas its occurrence is characterized by appearance a sub-synchronous vibration at speed onset. comparison experimentally obtained data prediction two degrees freedom dynamic model that includes flexible support characteristics, transverse inertia as well suggests excellent agreement both Eigenfrequency rotor Furthermore, effect stiffness moment critical onset has been investigated, led design guideline avoid bush In addition, experimental gathered after introduction damping significant increase