Acoustic characteristics of a multi-rotor MAV and its noise reduction technology

The present paper is devoted to identify the acoustic characteristic of a multi-rotor MAV, and then explore the effective noise reduction technologies for suppressing its high level noise. It is found that the noise is mainly generated by the high speed rotating propellers for a propeller-driven multi-rotor MAV. Surrounding the propellers on the MAV with the specially designed ducts is one of the effective methods for reducing the propeller noise. Thus various duct configurations, including non-perforated ducts, perforated ducts with different types of back cavities and membrane-type ducts are designed, fabricated using 3D printer and tested on a multi-rotor MAV. The acoustic performance of these ducts and their corresponding optimized designs are then analyzed and discussed for achieving a silent flying multi-rotor MAV.