Experimental and Analytical Investigation of Turbocharger Bearing-Rotor Dynamics
The objective of this investigation is to measure the dynamics of a turbocharger bearing and rotor system and be able to corroborate with analytical results, and therefore predict the performance of a turbocharger system under various loading and operating conditions. Traditionally turbochargers utilize journal bearings to support the rotating shaft. Recently though the movement has been to convert to using angular contact ball bearings. These bearings are more efficient as they have rolling contacts rather than sliding contacts as with journal bearings. This increase in efficiency will reduce lag time and engine fuel consumption. An electric motor driven Turbocharger Test Rig (TTR) has been developed to operate a two-stage high output turbocharger up to speeds of 75000 RPM. Another TTR is being developed to operate a single stage turbocharger up to speeds of 120,000 RPM using compressed air. Measurements on the system include vibrations and shaft motion and on the bearing include axial forces, radial forces, friction force, and the cage temperature. These measurements will be corroborated with analytical results, which will be determined using different models currently being developed within METL.
In addition, telemetry based, MEMS wireless temperature sensor has been developed and mounted on the bearing cage for in-situ monitoring of bearing condition.