It is required to examine the characteristics of turbochargers for automobiles using one-dimensional simulation from the viewpoint of estimating total engine performance. In this study, a mathematical model to predict mechanical loss generated in a turbocharger is proposed. Friction works generated in a journal bearing and a thrust bearing are modeled, separately. As for the calculation of the friction work with the thrust bearing, the thrust force is calculated from the fluid force which is

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... mulated analytically and calculated numerically based on one-dimensional flow taking account of relevant boundary conditions. According to the developed model, the friction work generated in a journal bearing is larger than that in a thrust bearing. Difference of thrust force and flow rate of oil has less impact on the friction works in a turbocharger. Finally, calculated total friction work based on the model proposed in the present study is compared with that obtained from the oil temperature method.