Study notes of turbocharger industry

Study notes of turbocharger industry

Measured rotor vibrations of an automotive turbocharger rotor were presented and the occurring dynamic effects explained. The main excited natural modes of the rotor/bearing system are the gyroscopic conical forward mode and the gyroscopic translational forward mode, both almost rigid body modes with slight bending. The measurements show that the system exhibits four main frequencies. The first main frequency is the synchronous vibration (Synchronous) due to rotor imbalance. The second dominating frequency is generated by the oil whirl/whip of the inner fluid films, which excite the gyroscopic conical forward mode. The third main frequency is also caused by the oil whirl/whip of the inner films, which now excite the gyroscopic translational forward mode. The fourth main frequency is generated by the oil whirl/whip of the outer fluid films, which excite the gyroscopic conical forward mode. Superharmonics, subharmonics and combination frequencies—created by the four main frequencies—generate the other frequencies, which can be seen in the frequency spectra. The influence of different operating conditions on the rotor vibrations was examined.

In a wide speed range, the dynamics of turbocharger rotors in full-floating ring bearings is dominated by oil whirl/whip phenomena occurring in the inner and outer fluid films of the floating ring bearings. Oil whirl/whip phenomena are self-excited vibrations, induced by the fluid flow in the bearing gap.

Reference

L. San Andres, J.C. Rivadeneira, K. Gjika, C. Groves, G. LaRue, A virtual tool for prediction of turbocharger nonlinear dynamic response: validation against test data, Proceedings of ASME Turbo Expo 2006, Power for Land, Sea and Air, 08–11 May, Barcelona, Spain, 2006.

L. San Andres, J. Kerth, Thermal effects on the performance of floating ring bearings for turbochargers, Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology 218 (2004) 437–450.