Influence of Pressure Distribution in the Turbine Casing on Blade Vibration of a Marine Turbocharger

One of the important goals in the design of a turbocharger is to reduce the resonance stress of the turbine blades. The resonance stress of a blade is influenced considerbly by fluctuations of the total pressure in the turbine casing. In this study, we have tried to explain the relationship between the total pressure fluctuation and the resonance stress during blade vibration. To evaluate this relation we measured the total and static pressures at various circumferential locations in a mixed-flow type turbine casing and used Fourier analysis to calculate the excitation force component caused by the total pressure fluctuations. Then resonance stress measurements were performed for the turbine blade in the same casing used for the pressure measurements. Experimental data show that resonance stress increases as total pressure fluctuation increases. Theoretical and experimental results show reasonable agreement.