Kamesh, PunithavathyBrennan, Michael J. [UNESP]Holmes, Roy2014-05-202014-05-202012-01-01Proceedings of The Institution of Mechanical Engineers Part C-Journal of Mechanical Engineering Science. London: Sage Publications Ltd, v. 226, n. C10, p. 2485-2495, 2012.0954-4062http://hdl.handle.net/11449/9912Automotive turbochargers, which operate at very high speeds, exceeding 180,000 r/min, exhibit two strong sub-harmonic modes of vibrations due to oil-whirl instability. These are a conical mode and an in-phase whirl mode. The gyroscopic effects can be very important in such a rotor system. This article presents a theoretical investigation into these effects on the conical whirl instability of a turbocharger induced by the angular (tilting) motion of a rigid rotor. A simplified linear model is used to analyse the rotor-bearing system by investigating the effects of the gyroscopic moment on the internal moments. A gyroscopic coefficient, defined by the geometry of the rotor, is shown to govern the stability of the conical whirl motion. A threshold value of 1/2 is determined for this coefficient to suppress the conical whirl. This value remains unaffected if the rotor is asymmetric and is supported by floating ring bearings, which is the case in a practical turbocharger.2485-2495engGyroscopic effectlinear analysisturbochargerconical whirl instabilityArtigo10.1177/0954406212438142WOS:000309206200009Acesso restrito