ON THE THEORY OF ACOUSTIC SOUNDING OF TUBULAR CHANNELS CONTAINING DEPRESSURIZATION PORTIONS

A study is made of the evolution of pressure perturbations that propagate in a tubular channel fi lled with liquid or gas and having a damaged portion in the form of fairly large slots when their hydraulic resistance is minor. For this purpose, the authors have adopted a mathematical model taking account of viscous friction and of the transfer of heat in a thin layer of the liquid (or the gas) near the wall. Based on this model, dispersion relations have been obtained for the processes of propagation and refl ection of harmonic waves from the damaged portion. An analysis has been made of the dependences of the phase velocity, the attenuation factor, and also the coeffi cients of refl ection and transmission on the circular frequency, the physical properties of the liquid or the gas, and also the size of damage. The authors have presented results illustrating the dynamics of pulsed signals as a function of the distance to the damaged portion from the inlet cross section of the channel, the damage scale, and of the form of the medium (liquid or a gas) in the channel.
   
Author:  V. Sh. Shagapov, É. V. Galiakbarova, and Z. R. Khakimov
Keywords:  harmonic wave, phase velocity, attenuation factor, thermal dissipation, pressure pulse, acoustic impedance, transmission and refl ection coeffi cients
Page:  663