Acoustic wave propagation analysis for detecting a sensor robot in heat transfer pipe

Ultrasonic Testings of heat transfer pipes in electric power plant are important. Those pipes, which are over 60 m and whose inner diameters are 25 mm, 50 mm, and 75 mm, have more than 20 curves and are located at directly unaccessible place. We developed a cableless robot for measuring thickness of pipe in a pipe filled with water but it is difficult to know where our robot is in the pipe at real time. We developed a projector to propagate an intensive single-mode wave into the pipes and examined the relations between frequencies-intenseness and wave propagation (3 kHz–50 kHz). Attenuations of acoustic waves in the pipe filled with water were much lager than those in the pie filled with air and examined for metal pipes and plastic pipes. Acoustic wave tunneling through pipe-wall was calculated and compared with experimental results. Acoustic wave tunneling through the pipe-wall was found to be the main reason why acoustic wave could not propagate longer in the pipe filed with water than that with air. We...