Browsing by Author "Lu, Zhenbo"

Now showing 1 - 3 of 3
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    Acoustic characteristics of a multi-rotor MAV and its noise reduction technology
    (Institute of Noise Control Engineering, 2016-08-21) Lu, Zhenbo; Debiasi, Marco; Khoo, Boo Cheong
    The present paper is devoted to identify the acoustic characteristic of a multi-rotor MAV, and then explore 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. Surrounding engine rotors with ducts designed to absorb their acoustic emissions is one of the methods typically used for reducing their noise. Thus two duct configurations, with non-perforated internal wall and with micro-perforated internal wall with back cavity, are designed, fabricated using 3D printing, and tested on a multi-rotor MAV. The acoustic performance of these ducts for achieving a quieter flying multi-rotor MAV are analyzed and discussed.
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    ItemOpen Access
    Bioinspired low-noise wing design for a two-winged flapping-wing micro air vehicle
    (American Institute of Aeronautics and Astronautics, 2018-10-15) Lu, Zhenbo; Debiasi, Marco; Nguyen, Quoc Viet; Chan, Woei-Leong
    This work investigates the acoustic and thrust performances of different wing designs for a two-winged flapping-wing micro air vehicle (FW-MAV). The reference wings, made of a Mylar film membrane supported by carbon-fiber rods, produce a perceived overall noise of about 68.8 dBA when operating at the flapping frequency of 10 Hz typically required for flying such a flapping wing vehicle. This noise is much higher than the value of the environmental background. Wings of various materials and structural configurations are designed and tested in order to reduce the flapping-wing noise. Sound and force measurements are used to assess their acoustic and lift capabilities. It is found that a wing made with a highly elastic dielectric elastomer membrane can reduce the overall perceived noise of the flapping wing by 12 dBA while slightly increasing the thrust. The mechanisms leading to this noise reduction and their potential applications in quiet FW-MAVs are discussed.
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    ItemOpen Access
    Low-noise flapping wings with tensed membrane
    (AIAA, 2020-04-15) Debiasi, Marco; Lu, Zhenbo; Nguyen, Quoc Viet; Chan, Woei Leong
    Micro air vehicles with flapping wings have the potential to be both more efficient and maneuverable than similar-sized fixed- or rotary-wing aircraft. Reducing the perceived noise produced by flapping wings without compromising or possibly enhancing their aerodynamic performance would be crucial in surveillance and military applications. To this aim, flapping wings have been designed and fabricated for which the supporting stiffeners tense the Mylar membrane to which they are bonded. The sound produced by these wings at different flapping frequencies has been recorded in an anechoic chamber simultaneously to the upward thrust they create. Comparing their characteristics and performance with those of flapping wings of conventional design suggests that tensing the wing’s membrane can increase the thrust while decreasing the typical rustling noise of the flapping wings