The Effect of Non-Circular Bearing Shapes in Hydrodynamic Journal Bearings on the Vibration Behavior of Turbocharger Structures

Abstract

Increasing quality demands of combustion engines require, amongst others, improvements of the engine's acoustics and all (sub)components mounted to the latter. A significant impact to the audible tonal noise spectrum results from the vibratory motions of fast-rotating turbocharger rotor systems in multiple hydrodynamic bearings such as floating bearing rings. Particularly, the study of self-excited non-linear vibrations of the rotor-bearing systems is crucial for the understanding, prevention or reduction of the noise and, consequently, for a sustainable engine acoustics development. This work presents an efficient modeling approach for the investigation, optimization, and design improvement of complex turbocharger rotors in hydrodynamic journal bearings, including floating bearing rings with circular and non-circular bearing geometries. The capability of tonal non-synchronous vibration prevention using non-circular bearing shapes is demonstrated with dynamic run-up simulations of the presented model. These findings and the performance of our model are compared and validated with results of a classical Laval/Jeffcott rotor-bearing model and a specific turbocharger model found in the literature. It is shown that the presented simulation method yields fast and accurate results and furthermore, that non-circular bearing shapes are an effective measure to reduce or even prevent self-excited tonal noise.

Effects of Hyperelliptic Bearings Bush on Connecting Rod Big-End Lubrication and Design Optimization

“…Bernhauser et al used the non-circular bearing shapes in turbocharger structures and found that non-circular bearing shapes are an effective measure to reduce or even prevent self-excited tonal noise [12].…”

Effect of the inlet oil temperature on vibration characteristics of the high-speed turbocharger rotor system

“…Feng and Ming 5 detailed the influence of outer film clearance on the floating-ring-bearing system stability. Bernhauser and Heinisch 6 proposed an efficient modeling method to simulate the self-oscillation of floating ring bearings. They found that the non-circular-bearing shapes are an effective measure to reduce or even prevent self-excited tonal noise.…”

Stability Effects of Non-Circular Geometry in Floating Ring Bearings

“…The theoretical analysis, which assumed a finite length bearing and solved the lubrication problem through the finite element method, made it possible to assess a better load capacity of the lobe geometry with respect to the reference circular one. Bernhauser et al [17] presented a run-up analysis of a TC multibody model with FRBs similar to those adopted in [15]. Regarding the practical employment of TCs within combustion engines, the authors pointed out the importance of imbalance-excite and self-excited TC vibration as responsible of disturbing tonal noise during the engine operation.…”