Stability Analysis of a Turbocharger for Marine Diesel Engine Service

Rotor stability is essential to the life span of any piece of rotating machinery; it becomes increasingly critical in high-speed machinery such as turbochargers. Large turbochargers, such as those found in marine diesel propulsion engines where the rotor alone often exceeds forty pounds, require careful consideration regarding stability as well as load support during the bearing selection process. Logarithmic Decrement is the primary consideration for rotor stability. Commercial software is used to model and analyze a proven unstable turbocharger rotor. After confirming that the model exhibits unstable characteristics, the same turbocharger is then analyzed with various fluid-film bearing configurations. Finally, the tilting-pad bearing is determined to be the best bearing for this turbocharger application, stabilizing the rotor throughout the entire designed operating range.