Abstract: Numerical mode matching (NMM) method is extended to calculate the acoustic attenuation performance of perforated tube reactive/dissipative silencers with mean flow,and the computational code is written.For the circular coaxial perforated tube reactive and dissipative silencers with mean flow,good agreements between the transmission loss results from NMM method and experiments are observed,which verified the accuracy of the present method and computational code.Then,the effects of flow convection and perforate impedance as well as perforated tube offset on transmission loss of perforated tube reactive/dissipative silencers are investigated by using NMM method.From the predictions it can be seen that,as the Mach number increasing,the acoustic attenuation of perforated tube reactive silencer increases in the mid to high frequency range and the acoustic attenuation of dissipative silencer is lowered in the whole frequency range;in the case of lower Mach number,the effect of flow convection on the acoustic attenuation performance of perforated tube reactive silencer is negligible,and the effects of convection and perforate impedance are noticeable at higher Mach number;for the perforated tube dissipative silencer,the effect of perforated impedance on the acoustic attenuation performance is smaller than that of the convection,and the difference with the real values is not neglected;the effect of perforated tube offset is dependent on frequency range and configuration of silencer.