Numerical Investigation of Aerodynamic Radial and Axial Impeller Forces in a Turbocharger

摘要

Aerodynamic forces are a major cause of turbocharger bearing friction. Thus, numerical simulations with ANSYS CFX are performed for a turbocharger turbine and compressor in order to determine these forces. Today, in common turbocharger CFD simulations the influence of the impeller backside cavity and blow-by are usually neglected. As a consequence, the axial forces on the impeller cannot be correctly determined. In this study therefore, the impeller backside cavity and blow-by were taken into account. Additionally, the influence of different operating conditions as well as different turbine and compressor blow-by flows were investigated. Finally, the resulting aerodynamic impeller forces of a turbocharger were analysed and visualized. The results show some trends which agree with the impeller forces of larger radial turbines and compressors published in literature. However some turbocharger-specific differences are identified, e.g. the wide operation range of a turbocharger. The influences of blow-by are found to be small but not negligible.