Resonance Frequency Shift in a Cylindrical Cavity with an Inner Small Coaxial Cylinder

Based on the perturbation theory, the resonance acoustic spectroscopy for a resonance cylindrical cavity with an inner small coaxial cylinder is investigated. Analytical expressions, in a cylindrical cavity with the rigid walls and traction-free ends, are derived for the acoustic resonance frequency shifts caused by the inclusion of a coaxially small cylindrical sample. The effects of various parameters on resonant frequencies of the resonant cavity are studied by numerical modeling in detail. The simulation results show that the lowest mode resonant frequency is very sensitive to the position of the sample. When the sample is located in the middle of the cylinder cavity, the resonant frequency gets its maximum and is more sensitive to the sample velocity. When the sample is located at two ends, the resonant frequency gets its minimum and is more sensitive to the sample density. Comparison of the experimental and theoretical values shows that their changing tendencies are in agreement qualitatively.