A turbocharger foerg_emd_ifme_atl_100k_v1_post_neu_date_2014_12_19_time_14_43_16_weißr a light-duty commercial vehicle is ramped up to 150,000 rpm. During run-up sub-harmonic oscillations occur, which are excited by the circulating oil. The amplitudes of the subharmonic vibrations are significantly greater than the unbalanced vibrations.

The jump frequencies and the amplitudes of the sub-harmonics depend on the geometry and the bearing clearance of the floating ring. The complete solution of the fluid film equation taking into account the misalignment and the oil supply conditions can be a very good predictor of the amplitudes and the jump frequencies. See also the examples in following publications:

„Numerical simulation of the dynamic behaviour of turbochargers under consideration of full-floating-ring bearings and ball bearings“

„Numerische Simulation des instationären Verhaltens der Schwimmbuchsenlagerung in Turboladern“

„Numerical run-up simulation of a turbocharger with full floating ring bearings“.

 

pressure distribution at 20,000 rpm in the full-floating ring bearing  (coupled inner and outer fluidfilm)

movement of the rotor at 20,000 rpm (exaggerated) – conical mode

pressure distribution at 45,000 rpm in the full-floating ring bearing  (coupled inner and outer fluidfilm)

movement of the rotor at 45,000 rpm (exaggerated) – cylindrical mode

pressure distribution at 140,000 rpm in the full-floating ring bearing  (coupled inner and outer fluidfilm)

movement of the rotor at 140,000 rpm (exaggerated) – conical mode