Vibration damping and noise reduction of MFC intelligent rotor based on frequency-domain dual LMS method

In helicopter rotor active vibration and noise reduction technology, smart torsional rotors based on Macro Fiber Composite (MFC) are considered as one of the most promising methods due to their lack of any additional mechanical components. Currently, most Active Torsion Rotor (ATR) vibration and noise reduction technologies based on MFC are still in the theoretical research stage. This paper uses MFC as the actuator and proposes a simple dual Least Mean Square (LMS) frequency-domain adaptive Higher Harmonic Control (HHC) algorithm for the smart torsional rotor based on the NACA23012 airfoil. Vibration and noise active closed-loop control experiments are conducted in a 3.4 m×2.4 m open-circuit wind tunnel. Compared to traditional frequency-domain HHC algorithms, the computational effort for single harmonic control is reduced by 5.5 to 11 times. Under various conditions, such as rotor speeds from 150 r/min to 210 r/min, wind speeds from 5 m/s to 10 m/s, and rotor shaft tilt angles of 0° and 8°, the controller reduces vibration levels by 27.24% to 58.55%. At a rotor speed of 210 r/min, wind speed of 10 m/s, and rotor shaft tilt angle of 0°, the controller can reduce noise levels by about 2.5 dB to 3.2 dB.