Date of Award

January 2015

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical Engineering

First Advisor

Farshid Sadeghi

Committee Member 1

John Starkey

Committee Member 2

Charles Krousgrill

Committee Member 3

Dimitrios Peroulis


The objectives of this investigation were to design and construct a high speed turbocharger test rig (TTR) to measure dynamics of differing turbocharger rotor bearing systems and to develop a coupled rotor-cartridge model for the ball bearing rotor system to corroborate the experimental and analytical results. The ball bearing rotor is supported by an angular contact ball bearing cartridge. In order to achieve the objectives of the experimental aspect of this study, a TTR was designed and developed with the capability of reaching speeds in excess of 100,000 rpm driven by compressed air. The TTR was used to compare and contrast the whirl and friction characteristics of two identical turbochargers differing only by the support structure of the rotor system; one containing a floating ring bearing turbocharger (FRBT) and the other a ball bearing turbocharger (BBT). A pair of displacement sensors was installed to measure the whirl of the rotor near the end of the compressor. The BBT was shown to be significantly more rigid and stable as compared to the FRBT with an average reduction in radial rotor motion of 47%. The motion of the BBT consisted of mainly synchronous motion whereas the FRBT was dominated by subsynchronous motion throughout the entire range of speeds. The TTR was also used to compare frictional losses within the bearings. A study of run-down times after the pressurized air supply was removed indicated that the BBT has significantly lower frictional losses under all operating conditions tested with an average increase in run-down time of 14.1%.