To analyze the acoustic propagation of aircraft engine nacelle

predicting the acoustic propagation of a varying cross-section ducted-fan with finite thickness

the fast scattering method was discussed.The ability of the method in application to the sound propagation problems with different pipeline thickness of ducted-fan shapes

including the equal circular tube and variable cross-section tube has been demonstrated.If the pipeline thickness is more than 2 percents of the radius

the pipeline thickness should not be ignored in the prediction of the scattering sound field.The present method provides the theory basis for choosing the ducted-fan thickness in the engineering.