Radial turbines with nozzle guide vanes are widely used in various size turbochargers.However,due to the interferences with guide vanes,the blades of impellers are exposed to intense unsteady aerodynamic excitations,w...Radial turbines with nozzle guide vanes are widely used in various size turbochargers.However,due to the interferences with guide vanes,the blades of impellers are exposed to intense unsteady aerodynamic excitations,which cause blade vibrations and lead to high cycle failures(HCF).Moreover,the harmonic resonance in some frequency regions are unavoidable due to the wide operation conditions.Aiming to achieve a detail insight into vibration characteristics of radial flow turbine,a numerical method based on fluid structure interaction(FSI) is presented.Firstly,the unsteady aerodynamic loads are determined by computational fluid dynamics(CFD).And the fluctuating pressures are transformed from time domain to frequency domain by fast Fourier-transform(FFT).Then,the entire rotor model is adopted to analyze frequencies and mode shapes considering mistuning in finite element(FE) method.Meanwhile,harmonic analyses,applying the pressure fluctuation from CFD,are conducted to investigate the impeller vibration behavior and blade forced response in frequency domain.The prediction of the vibration dynamic stress shows acceptable agreement to the blade actual damage in consistent tendency.展开更多
基金funded by the National Natural Science Foundation of China(No.51176013)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20111101130002),China
文摘Radial turbines with nozzle guide vanes are widely used in various size turbochargers.However,due to the interferences with guide vanes,the blades of impellers are exposed to intense unsteady aerodynamic excitations,which cause blade vibrations and lead to high cycle failures(HCF).Moreover,the harmonic resonance in some frequency regions are unavoidable due to the wide operation conditions.Aiming to achieve a detail insight into vibration characteristics of radial flow turbine,a numerical method based on fluid structure interaction(FSI) is presented.Firstly,the unsteady aerodynamic loads are determined by computational fluid dynamics(CFD).And the fluctuating pressures are transformed from time domain to frequency domain by fast Fourier-transform(FFT).Then,the entire rotor model is adopted to analyze frequencies and mode shapes considering mistuning in finite element(FE) method.Meanwhile,harmonic analyses,applying the pressure fluctuation from CFD,are conducted to investigate the impeller vibration behavior and blade forced response in frequency domain.The prediction of the vibration dynamic stress shows acceptable agreement to the blade actual damage in consistent tendency.
