ATTENUATION OF HIGHER ORDER CIRCUMFERENTIAL THERMOACOUSTIC WAVES IN VISCOUS FLUID LINES

Abstract The acoustic waves propagation in viscous water, glycerin and air contained in a rigid wall, thermally insulated, infinite long, circular tube are studied using the exact three-dimensional thermal-fluid coupled equations for the vibrations in the n = 0, 1 circumferential modes. The first three axially symmetric modes at n = 0 and the first three non-axially symmetric modes at n = 1 are presented. The corresponding two-dimensional mode shapes are plotted so that the wave vibrations can be identified. It is found that the dispersion spectra, mode shapes and phase velocity dispersion plots of the three fluid mediums are very close. But the attenuation rates of glycerin and air are about 37 and 9 times higher than water, respectively.