Bionic Composite Structure-Based Self-Noise Suppression Method for Towed Arrays

Abstract This paper addresses the hydrodynamic self-noise issue in towed line arrays induced by turbulent boundary layers at medium-to-high tow speeds, proposing a composite noise reduction method that integrates bionic groove structures with dynamic mucus coatings. Inspired by the microscopic grooves on shark skin and the mucus secretion mechanism of fish, V-shaped grooves with varying geometric parameters were arranged on the array surface to effectively suppress the development of streamwise vortices in the turbulent boundary layer and reduce turbulent pressure fluctuations. Simultaneously, a mucus jet system was deployed upstream of the working section to form a dynamic mucus coating, further enhancing flow field control. Numerical simulations combining Large Eddy Simulation (LES) and acoustic analogy theory, along with experimental validation, were employed to systematically analyze the influence of parameters such as groove width on noise reduction performance. The results demonstrate that grooves with smaller aspect ratios (e.g., a central angle of 4°) achieve significant noise reduction in the 500–2000 Hz frequency band. When combined with mucus jetting, the noise reduction bandwidth is further expanded, and low-frequency peak noise is suppressed. The underlying mechanism primarily stems from the synergistic effects of energy dissipation by secondary vortices within the grooves and the thickening of the viscous sublayer due to the mucus. Experimental results from a gravity-based low-noise water tunnel further verify the effectiveness of this composite method in reducing self-noise sound pressure levels, providing a novel technical approach and theoretical basis for the acoustic stealth design of towed line arrays.