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UID:0-542@aerospace.technion.ac.il

DTSTART;TZID=Asia/Jerusalem:20230906T133000

DTEND;TZID=Asia/Jerusalem:20230906T143000

DTSTAMP:20230725T063710Z

URL:https://aerospace.technion.ac.il/events/towards-abatement-of-quadrotor
 s-acoustic-signature-with-phase-control-technology/

SUMMARY:Towards Abatement of Quadrotor’s Acoustic Signature with Phase Co
 ntrol Technology
DESCRIPTION:Lecturer:Ofek Hertzman \n Faculty:Department of Aerospace Engin
 eering\n Institute:Technion – Israel Institute of Technology\n Location:
 Classroom 165\, ground floor\, Library\, Aerospace Eng\n Zoom: https://tec
 hnion.zoom.us/j/97346140543\n Abstract: The annoying sound produced by a m
 ulti-rotor vehicle can bring a severe acoustic nuisance to an urban sounds
 cape. Hence\, it is paramount to find a solution to attenuate the acoustic
  signature of a multi-rotor platform for further public development and ac
 ceptance of these vehicles. In the scope of the MSc thesis\, a phase contr
 ol technique was applied to attenuate acoustic signature\, and the feasibi
 lity and potential are explored through an experiment. The noise reduction
  technique leverages destructive interference of the coherent acoustic sou
 rce field between a system of propellers by controlling the relative phase
  between the blades in a multi-rotor configuration. In the first stage\, a
  low-noise and aerodynamically efficient single-rotor configuration based 
 on APC 14x5.5 propeller was designed. The design was based on modelling th
 e static aerodynamic loads on the blade with Blade Element Momentum Theory
 . The assumption is that aerodynamic efficiency will result in the reducti
 on of the sound propagation of the blade. In the second stage\, single and
  multi-rotor configuration experiments were studied experimentally.\n\nThe
  single and the multi-rotor configurations were part of a measurement camp
 aign conducted in the newly established anechoic chamber at the Faculty of
  Aerospace Engineering at the Technion - Israel Institute of Technology. A
 n array of 15 microphones were placed 1.5 meters away from the center of t
 he rotors' rig on a spherical arc. In the multi-rotor configuration\, by c
 arefully selecting the relative azimuths blade angle (phase)\, the overall
  sound pressure directivity and level of the tonal component at the blade 
 passage frequency can be attenuated. It was found that with destructive in
 terference\, a 90 degrees of phase angle between neighbouring rotors\, a r
 eduction of 4 dB at 3000 RPM and by 7 dB at 3800 RPM was observed\, compar
 ed to uncontrolled configuration. Measured sound pressure levels were comp
 ared to the analytical acoustic model\, and similar amplitudes and trends 
 of the sound pressure levels were found between the model and the measurem
 ents.\n Details: \n 
CATEGORIES:Seminars
LOCATION:Classroom 165\, ground floor\, Library\, Aerospace Eng

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