Investigation on forced vibration of turbocharger turbine in pulsation flow

Variable guide vanes turbines are widely applied in turbocharger. To assess the effects of pulsation inlet conditions on the aerodynamic excitation and the forced vibration of turbine wheel, the weak fluid structure interaction method was adopted. Firstly, a pulsation flow with the frequency of 60 Hz (which corresponds to the engine speed of 2400 r/min) was applied at the turbine inlet to conduct the unsteady flow calculation. The results show that the aerodynamic loads are highly influenced by the pulsation inlet conditions, which fluctuate with the inlet pulsation wave in a pulse cycle, and the maximum and minimum blade load corresponding to the peak and trough of the inlet pulsation wave respectively. For the forced vibration analysis of turbine wheel, the calculated aerodynamic loads in pulsation flow were imposed as the loading boundaries to perform the harmonic vibration and transient structural response by FE calculations, based on the natural frequency and mode of the blade disk. The results show that the forced response of the blade disk not only reflects the contribution of low frequency pulsation excitations but also contains the high frequency pressure fluctuations caused by rotor rotation.