Study on vibration response characteristics of turbine blade for turbo-charger

Abstract

In the mechanical design of a turbine blade for an automotive turbo-charger, it is pointed out that the mistuning effect caused by the difference of the casting condition should be considered. Namely, the difference of the 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, the reduced order model FMM (Fundamental Mistuning Model) is applied to evaluate the resonant response of mistuned system. First, the frequency response analysis of mistuned system is carried out, using both of the FMM and the direct FEM, and the calculated results are compared to confirm the validity of the FMM. Second, the frequency response analysis of mistuned system is carried out using the FMM, the Monte Carlo simulation and the optimal method to examine the effect of various parameters on the maximum response of a mistuned system. In addition, the effect of the intentional mistuning on the reduction of the maximum response is researched using the genetic algorithm.

Keywords

• turbomachinery
• forced vibration
• blade
• mistuning
• optimal design