Experimental and Analytical Investigation of High Speed Turbocharger Ball Bearings

Abstract

The objectives of this investigation were to design and construct a high speed turbocharger test rig (TTR) to measure dynamics of angular contact ball bearing rotor system, and to develop a coupled dynamic model for the ball bearing rotor system to corroborate the experimental and analytical results. In order to achieve the objectives of the experimental aspect of this study, a test rig was designed and developed to operate at speeds up to 70,000 rpm. The rotating components (i.e., turbine wheels) of the TTR were made to be dynamically similar to the actual turbocharger. Proximity sensors were used to record the turbine wheel displacements while accelerometers were used to monitor the rotor vibrations. The TTR was used to examine the dynamic response of the turbocharger under normal and extreme operating conditions. To achieve the objectives of analytical investigation, a discrete element ball bearing model was coupled through a set of interface points with a component mode synthesis rotor model to simulate the dynamics of the turbocharger test rig. Displacements of the rotor from the analytical model were corroborated with experimental results. The analytical and experimental results are in good agreement. The bearing rotor system model was used to examine the bearing component dynamics. Effects of preloading and imbalance were also found to have significant effects on turbocharger rotor and bearing dynamics.