Microbearings - new tribology problems and challenges
Journal Title: Tribologia - Year 2009, Vol 227, Issue 5
Abstract
Nonlinear forms of vibrations in rotors dynamics, especially after exceeding the stability limit, as well as the assessment of not precise and randomly variable input parameters still constitute the research subject in many institutions all over the world. The results of investigations of the high-speed rotor of a micro turbine being an element of the micro power plant in dispersed power engineering based on renewable energy sources are presented in the paper. The basic problem of such devices is to assure a stable rotor operation within the entire range of rotational speeds. Foil bearings and special rotor structure were applied. It turned out that the situation, in that the rotor – after loosing its stability – stabilizes again when the rotational speed increases, is possible. This is a new phenomenon determined by the author as ‘multiple whirls’. Possibilities of stabilizing the situation by the application of hybrid lubrication and siphon pockets are also presented in the paper. Another topic discussed in the hereby paper is an assessment of the influence of a random character of certain input data – in this case – changes of external excitations of the system. This problem is related to the so-called heuristic models often placed in opposition to widely used algorithmic models. The obtained results indicate different influence of disturbances depending on the system working conditions. After exceeding the stability limit, it means in a highly nonlinear operation range, the influence of disturbances significantly decreases. It is rather unexpected result. Research tools such as computer series codes and the method of their experimental verification are also included in the paper.<br/><br/>
Authors and Affiliations
Jan Kiciński
Keywords
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