Flow noise suppression in a cavity via electromagnetic force: A multi-physics analysis of its mechanism

Cavity flow noise, driven by flow separation and vortex interactions, poses a persistent engineering challenge. This work proposes a novel electromagnetic-force-based active control strategy and elucidates its suppression mechanism through a coupled multi-physics framework integrating electromagnetic, flow, and acoustic fields. The Lorentz force, generated by near-wall electrodes and magnets, achieves significant noise attenuation. The overall sound pressure level drops by 7.82 dB at typical monitoring points and by up to 10.62 dB in the far-field lateral direction. The cavity flow is fundamentally restructured. The number of dominant vortex systems reduces from four to three, and the main vortex enlarges and protrudes out of the cavity, lifting the main flow and weakening the Rossiter–Heller acoustic feedback loop. Crucially, the Lorentz force modulates the classical energy cascade. Horizontal and vertical integral scales decrease by 51% and 37%, respectively, and structure–function analysis reveals an anomalous scaling exponent, indicating a non-Kolmogorov cross-scale energy redistribution. By injecting near-wall momentum, the electromagnetic force enhances small-scale horizontal fluctuations while suppressing vertical ones, thereby attenuating both dipole and quadrupole sound sources. Parameter sensitivity further demonstrates that noise reduction scales with applied voltage, with an optimal balance between performance and energy cost at a voltage of ±1.875 V. This multi-physics investigation not only establishes an effective cavity-noise suppression technique but also uncovers the underlying energy-transfer modification, offering a new pathway for flow-noise control in reverberant environments.