Abstract: The three-dimensional time-domain approach is used to investigate the effect of grazing flow on the acoustic impedance of perforated plate.The CFD(Computational Fluid Dynamics) simulation model for the acoustic impedance of perforated plate with grazing flow is built and the perforation acoustic impedance is evaluated by the CFD computation in time domain.The effects of structural parameters and grazing flow on the perforation acoustic impedance are analyzed.Based on the numerical results,the curve-fitting expressions for perforation acoustic impedance are provided. In combination with the perforation acoustic impedance with grazing flow,the transmission loss of perforated tube silencers is predicted and good agreements between the numerical predictions and measurements are observed.The results demonstrated that the grazing flow influences obviously the perforation acoustic impedance and the acoustic attenuation characteristics of perforated tube silencers.