Numerical Analysis for Active Noise Control of Rotor Based on Dynamic Variable-diameter Method

Helicopters in high-speed forward flight often generate High-Speed Impulse (HSI) noise, presenting a major challenge for noise control and narrowing the range of helicopter use. This paper proposes a novel method for active noise reduction by adjusting the rotor diameter length, effectively delaying HSI noise onset and reducing HSI noise impact. Utilizing the CLORNS solver and the Ffowcs Williams-Hawkings (FW-H) equation, this approach was tested on the AH-1G rotor through simulation analysis. The study simulated the rotor's dynamic diameter length changes, analyzing the effect of crucial parameters on the sound field. Results indicate that this method significantly controls the production of rotor high-speed pulse noise, achieving a noise reduction of up to 2dB at critical operational points. This research aids in formulating specific rotor noise control laws and expands the range of scenarios for helicopter usage.