Bifurcation Analysis of Turbocharger Flexible Rotor System Supported on Fluid Film Bearings

The finite element model of the turbocharger flexible rotor system supported on fluid film bearings has been developed using Timoshenko beam elements. The bearing forces acting on the journal are derived from the Reynolds lubrication equation using Ocvirk's short bearing assumption and Half Sommerfeld boundary condition. The second-order governing differential equations of the motion of turbocharger system has been reduced to first-order equations using state-space variables. MATLAB (R) routine ode 15s solver has been adopted to solve the differential equations of the system, and the transient response of the journal centers is computed. The orbital plots, phase portraits, and bifurcation plots have been used to describe the behavior of the turbocharger system.