On the Instability Threshold of Journal Bearing Supported Rotors

Autor(es)

Mendes, Ricardo Ugliara ; Cavalca, Katia Lucchesi

• Tipo de documento: Artigo Científico
• Fonte: INTERNATIONAL JOURNAL OF ROTATING MACHINERY; v. 2014, p. 17-pg., 2014-01-01.

Resumo

Journal bearing supported rotors present two kinds of self-excited vibrations: oil-whirl and oil-whip. The first one is commonly masked by the rotor unbalance, hence being rarely associated with instability problems. Oil-whip is a severe vibration which occurs when the oil-whirl frequency coincides with the first flexural natural frequency of the shaft. In many cases, oil-whip is the only fluid-induced instability considered during the design stage; however, experimental evidences have shown that the instability threshold may occur much sooner, demanding a better comprehension of the instability mechanism. In this context, numerical simulations were made in order to improve the identification of the instability threshold for two test rig configurations: one on which the instability occurs on the oil-whip frequency, and another which became unstable before this threshold. Therefore, the main contribution of this paper is to present an investigation of two different thresholds of fluid-induced instabilities and their detectability on design stage simulations based on rotordynamic analysis using linear speed dependent coefficients for the bearings. (AU)

• Processo FAPESP: 07/54647-4 - Comportamento dinâmico e controle ativo de vibrações em máquinas rotativas sobre mancais hidrodinâmicos
• Beneficiário: Katia Lucchesi Cavalca Dedini
• Modalidade de apoio: Auxílio à Pesquisa - Regular