EXPERIMENTAL RESEARCH ON LONGITUDINAL MODE SELECTION IN PIPES USING ANGLE BEAM PROBES

The excitation and reception of higher order longitudinal modes are investigated experimentally. According to Snell’s law and phase velocity dispersion curves, incident angles and excitation frequencies of angle beam probes are chosen, and then, the wanted subsequently higher order longitudinal modes are excited in pipes. However, it will become more difficult to control excited modes as the order and excitation frequency of longitudinal modes become higher. Furthermore, the influence of the number of excitation angle beam probes on mode choice is analyzed. Experimental results show that it is essential to suppress flexural modes by increasing the number of excitation angle beam probes.