| dc.description.abstract | Linear models to identify critical points of operation
depend largely on linear coefficients representing film
lubrication, in which the shaft is supported, and the
exciting forces of the shaft. However, the magnitudes
of the coefficients of the oil film determined in rotational
dynamics studies of small turbochargers (TC)
still have great uncertainty. In present paper the linear
coefficients of the film hydrodynamic lubrication in
automotive turbocharger with semi-floating bearings
have been estimated using different methodologies.
These methodologies are based on the resolution of
the film lubrication Reynolds equation using different
approaches. These approaches are short bearing
and long infinite bearing. Different tests have been
made with various magnitudes with a synchronous
frequency to generate excitation forces on the compressor
and turbine wheels. At the end, the input
parameters of the model (linear coefficients of the
lubrication film and synchronous forces) are fitted in
order to predict the measured orbit described by the
shaft tip on the compressor side. The main critical operation
points have been identified by a Campbell diagram.
These points are related with the synchronous
frequencies of the shaft. The obtained results have
been compared with experimental measurements. | |
