Automotive turbochargers, which operate at very high speeds, exceeding 180,000 r/min, exhibit two strong subharmonic 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 lA 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.
On the stabilising effect of gyroscopic moments in an automotive turbocharger
Über die stabilisierende Wirkung von Kreiselbewegungen in einem Abgasturbolader
2012
11 Seiten, 9 Bilder, 11 Quellen
Article (Journal)
English
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