Study on the generation mechanisms of hydrodynamic noise in underwater glider wings based on bidirectional fluid–structure interaction

Underwater gliders (UGs) integrating multiple sensors have become crucial platforms for marine observation and detection. When subjected to fluid forces, UGs equipped with acoustic payloads at wingtips exhibit reduced measurement fidelity due to the substantial hydrodynamic noise. This study systematically explores the generation mechanisms of hydrodynamic noise in glider wings by coupling numerical and experimental validation. First, the bidirectional fluid–structure interaction method is implemented for numerical simulation, yielding time–history structural dynamics and transient flow field characteristics around the wing. Subsequently, an improved Lighthill's acoustic analogy is developed to transform flow field characteristics into noise sources, enabling numerical analysis of hydrodynamic noise. Additionally, the dominant hydrodynamic noise sources are identified through integrated analysis of flow field characteristics and wet modal simulation, with their sound pressure level primarily concentrated in a low-frequency band (0–200 Hz). The results indicate that peak frequencies (4, 11, 21, 40, 53, and 61 Hz) of flow noise are mainly attributed to flow separation near the leading edge and its associated vortex structures, while peak frequencies (89, 109, and 129 Hz) of flow-excited noise are predominantly governed by wing modal responses. Finally, the modal testing and sea trial of the glider demonstrate that discrepancies between experimental and simulation results are within 10%, confirming the origin of peak-frequency hydrodynamic noise. These findings provide critical insights for optimizing glider wing designs to suppress hydrodynamic noise.