To address the significant challenges posed by operational noise from underwater vehicles in scientific exploration and engineering applications, this study investigates the active control of flow-induced noise on a hydrofoil using streamwise electromagnetic force (EMF). Utilizing a combined approach of large eddy simulations (LES) and experimental validation, we comprehensively analyze the hydrodynamic, wall-pressure fluctuation (WPF), and acoustic characteristics of a NACA0018 hydrofoil at Rec=1.26×106 and an angle of attack of 6°, both with and without EMF control. Numerical results reveal that EMF effectively mitigates large-scale flow separation and delays boundary layer transition by enhancing near-wall momentum and restructuring turbulent dynamics, leading to a substantial reduction in WPF intensity, particularly suppressing the low-frequency, high-energy fluctuations associated with separation. Through data-driven analyses, prominently spectral proper orthogonal decomposition (SPOD), complemented by continuous wavelet transform (CWT) and k−ω spectra analyses, we demonstrate that EMF disrupts dominant coherent structures, reduces their downstream propagation velocity, and decreases the spanwise correlation length of WPF, thereby diminishing the effective radiation size of noise sources. Consequently, both numerical simulations and experimental measurements show significant broadband reductions in radiated sound power level, with overall attenuation reaching up to 7.37 dB in simulations (50–2000 Hz) and 7.14 dB in experiments (500–2000 Hz). These findings confirm that EMF control effectively suppresses flow-induced noise by fundamentally altering boundary layer flow structures and turbulent dynamics. This study provides critical physical insights and technical guidance for the low-noise design and advanced applications of underwater vehicles.
Qin et al. (Thu,) studied this question.
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