Analyses on dispersions and excitations of symmetric guided waves in a fluid-filled cylindrical shell

To develop a new calibration standard of acoustic logging, we studied the wave propagation in a fluid-filled cylindrical shell with outside traction-free boundary conditions. We obtained the phase- and group- velocity dispersions as well as the excitation spectrum curves. Numerical results show that when the frequency of source becomes higher and reaches in the “plateau” range, the first-arrival wave is just the mode with “plateau” characteristics. When the source frequency is in a range between two “plateaus”, the first-arrival wave is nearly the sum of two modes which have almost the same excitation intensities and group velocities. Coincidentally, the average phase velocity of the two modes is very close to the “plateau” velocity. Such a phenomenon can be used for the calibration of sonic logging tools.