Study on acoustic time delay localization in boiler tube arrays considering effective sound velocity

Based on the study of sound propagation characteristics and acoustic radiation in periodic tube arrays, we found that the wave front differed from the no-tube arrays at the same frequency. The phenomenon indicated that there was different sound velocity in tube arrays. This research considered tube arrays as an effective medium for sound and studied the effective sound velocity at different frequencies in tube arrays. The numeral calculations and experiments shown similar conclusions that the sound velocity was slower than in no-tube arrays one. Acoustic velocity directly affects the accuracy of time delay localization method, and the time delay localization method in acoustic isotropic media is mature. The velocity of low frequency sound wave is isotropic in the arrays, we investigate the variation of sound velocity theoretically and experimentally. The sound demonstrates anisotropy at high frequency region, the effective sound velocity is related to the band gap in the tube arrays. The research has been found that the same frequency has different sound velocity values in different directions. In different directions of tube arrays, the effective sound velocity is used to conduct an one-dimensional acoustic source location experiment. This study can provide an innovative concept and method for leakage location in boiler tube arrays.