The dynamic behaviour of an automot

The dynamic behaviour of an automotive turbocharger supported with full floating ring bearings is investigated experimentally and numerically. The rotor orbit on compressor side and, after modifying the turbocharger’s housing, the rotational speed of the floating ring are investigated by the measurement. To determine the ring’s rotational speed, the housing of the journal bearing section has been rebuilt employing a transparent synthetic material. The floating ring on the compressor side is now visually accessible. Using a high-speed camera and a subsequent image analysis in Matlab, the communication holes around the circumference of the floating ring are detected and the rotational speed can be calculated afterwards.

These experimental results are compared with a numerical rotor model. The model simulates a flexible rotor with four translational degrees of freedom and a finite- volume-model of the journal bearings. The numerical results show the subsynchronous limit cycles, which can also be seen in the measurements. The results of the numerically calculated rotational speed of the floating ring and the calculated subsynchronous frequencies in comparison to the experimental results conclude this paper.