الفهرس 
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Abstract
Thesis Summary
This thesis is concerned with the evaluation of the factors affecting turbocharger service life and introduces an experimental-based approach to measure the shaft/bearing clearance of turbocharger without dismantling the assembly.
An experimental test rig was designed, constructed, and provided with computer-based sensors to measure and record the test data for further analysis and interpretation.
The test rig consisted of a set of shaft/bearing assembly with known different clearances. It is connected to a constant volume air tank through piping and connectors to allow the tank to discharge through the known clearance. The tank pressure and temperature were measured using pressure and temperature transducers and their signals were transmitted to the computer through the proper interface.
By means of the constructed test facility, the variation of the tank pressure and temperature are examined in the time domain and are related to the known clearances.
Reference curves are constructed in order to use them to determine the shaft/bearing clearance of turbochargers in site without dismantling them, which fulfils the objective of this work.
Good estimation was obtained and verified with theoretical analysis using isothermal, isotropic and polytropic models.
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It is concluded that the theoretical model for discharge process that gives good approximation with the experimental results is the polytropic model and the average polytropic index “n=1.01”.
the polytropic model depends on the instantaneous value of the index and it is almost equal to one “ni =1” which is the same value for the isothermal index.
Keywords: Turbocharger failure; Shaft/bearing clearance estimation; Service life