Wave properties and band gap analysis of deploying pipes conveying fluid with periodic varying parameters

Abstract

Wave propagation and band gap (BG) characteristics of deploying long pipes conveying fluid are investigated based on a phononic crystal (PC) pipe model. The dispersion relation of the corresponding time-variant uniform pipe system is first derived in terms of the traveling wave feature of axially moving structures. Basic wave properties, such as the propagating and evanescent waves and the phase velocity and group velocity of propagating waves, are discussed to demonstrate the great effects of the flow velocity and deploying speed. The band structures of deploying pipe conveying fluid with periodic varying parameters are then investigated based on the Bragg scattering mechanism and treated by the transfer matrix method. A complex propagation constant is used to measure the band distribution. The fluid–structure interaction, deploying motion and component geometry are all found to have significant effects on the location and width of the BGs of the pipe. The deploying speed and flow velocity mainly influence the lower BGs while the component geometry acts much on the higher ones.