Study of Rotor Vibration due to the Rubbing against Casing: The Influence by Offset of Rotor and Casing

With rapid advances in a technology of industry, rotating machinery tend to be more high speed and performance. This tendency might be considered the main cause that induced numerous vibration troubles in the field of rotating machinery. Recently, in order to increase the machines performances the radial clearance between rotor and casing became smaller and smaller. As a result, severe vibration accidentally occurred in the rotating mechinery systems. Especially in the case of high-speed domain, various kinds of vibration occurred, such as “collision type synchhonous vibration”, “sub harmonic vibration”, etc. In the former paper, it was reported that the effects of casing dynamics and configurations of the casing for generating sub-harmonic vibration of rotor due to rubbing. furthermore, in this paper, it investigated what influence the offset of rotor and casing would have on generating of sub harmonic vibration, theoretically and experimentally.