In order to reduce rotor low frequency in-plane harmonic noise

a noise measuring system and a control system were developed accordingly and a frequency-domain active control method was proposed based on the integrated test rig of electrically controlled rotor(ECR). Then the close-loop active control experiments of low frequency in-plane harmonic noise using ECR were performed in hover state. During the experiment

the control frequency of the flap was 10Hz

the noise signal captured by the microphone in plane was used as feed-back signal and the noise signals captured by the other two microphone were used for monitoring. At the same time the vibration lever of the hub was monitored. After control

the control system took 5s to enter into a steady state

the convergence speed was fast and there was no obvious overshoot during convergence. 9.4dB noise reduction was possible at the location of the microphone in plane

and the vibration level of the hub increased a little. Experiment results showed that the developed control system was effective and reliable in reducing low frequency in-plane harmonic noise through the tests

and the feasibility and effectiveness of the frequency-domain active control algorithm in reducing low frequency in-plane harmonic noise were validated.