In the mechanical design of a turbine blade for an automotive turbocharger, it is pointed out that the mistuning effect caused by the difference of casting condition should be considered. Namely, the difference of casting condition causes the small variation of Young's modulus of each blade on a turbine wheel. These small variations break the cyclic symmetry, and split the eigenvalue pairs. In the forced response of a mistuned system, the responses of all blades become different, and the response of a certain blade may become extremely large due to splitting of the duplicated eigenvalues and distortion of the vibration modes. In this study, as a reduction method for the resonant response of mistuned turbine wheels, asymmetric vane spacing is examined systematically using the reduced order model FMM and the Monte Carlo simulation. It is shown that asymmetric vane spacing is a practical method for reducing resonant responses.
