Towards efficient and vibration-reducing full-floating ring bearings in turbochargers

Turbocharger rotors supported on full-floating ring bearings are highly nonlinear systems which operate at high speeds. During operation, the rotor usually oscillates at sub-synchronous frequencies which result from fluid-induced instabilities. This work provides some suggestions for reducing the sub-synchronous vibrations and power losses in the bearings. These are reduced by introducing new designs for lubrication grooves which are described in detail and thoroughly analysed. Furthermore, it is shown that subtle changes in the geometry of an inner film can influence the stability of an outer film in the floating ring bearing. The motion of the turbocharger rotor is described employing flexible multi-body dynamics. Forces in the floating ring bearings are evaluated numerically and flow through feed holes which are interconnecting the inner film with the outer film is considered.