Influence of Turbocharger Rotational Speed on Logarithmic Decrement and Stimulus Value of Turbine Blade

In response to recent requirements for diesel engines with higher output, IHI has started developing a turbocharger having a higher pressure-ratio and volume-flow rate. One important technology for design of the turbocharger is a means of accurately evaluating the strength of turbine blades at resonance operating condition, in which serious accidents may occur through a failure of the blades now on the market. In this study, we measured resonance stress, resonance frequency, and logarithmic decrement for fluctuating flow and for non-fluctuating flow in the turbine scroll of the turbine casing. We describe the result of blade vibration measurements that were performed to clarify the influence of fluctuating flow on the resonance stress. The acquired results will contribute to safe design of a new turbine casing and turbine blade.