Study on the Acoustic Scattering Characteristics of Non-Spherical Bubbles in Water

To address the challenge of active acoustic detection of underwater gas leakage, this study focuses on freely rising single non-spherical bubbles as the research object. A combined acoustic-optical observation experimental platform is established to synchronously acquire dynamic behavioral data during bubble ascent and acoustic scattering target strength (TS) measurements in an underwater acoustic experimental tank. The acoustic scattering characteristics of single bubbles are systematically analyzed over the 70–120 kHz frequency band. Three distribution models—Chi-square, Rice, and Normal—are employed to fit the random fluctuations observed in the experimentally derived TS statistics; the Kolmogorov–Smirnov (K–S) test is used to evaluate the goodness-of-fit of these statistical models. Meanwhile, based on a binocular vision algorithm, 3D morphological reconstruction of individual bubbles is performed, and simulation calculations are conducted to verify consistency between simulated and experimental mean TS values (with a deviation of < 3 dB). Furthermore, a Monte Carlo model based on randomly oriented ellipsoids is developed for statistical analysis of the scattering cross-section. Results indicate that the statistical distribution of target strength fluctuations for single non-spherical bubbles is best described by the chi-square (χ²) distribution. This integrated acoustic-optical approach provides reliable theoretical and experimental support for studying acoustic scattering from underwater non-spherical bubbles and offers valuable reference data for underwater gas leakage detection.