On the effect of unsteady motions on the rotor aerodynamic noise

Siyang Zhong, Peng Zhou, Hanbo Jiang, Han Wu, Jingwen Guo, Xin Zhang

Research output: Unpublished conference presentation (presented paper, abstract, poster)Conference presentation (not published in journal/proceeding/book)Academic researchpeer-review


This work presents a parametric study of the effects of rotational speed variation and blade vibration on the aeroacoustic characteristics of the fixed-pitch rotors. The study is based on an efficient prediction of the rotor noise with the effect of unsteady motions, including the fluctuations in the rotation speed and blade vibration, considered. The flow variables are computed using a cost-effective blade element and momentum theory method to evaluate the equivalent sound sources. The amplitudes of the unsteady motions are small. The computation results showed that periodic rotation speed fluctuations and blade vibrations could produce multiple tones in the combination of the blade passing frequency and the frequency of the fluctuation. By contrast, random rotation speed fluctuation or blade vibration can increase the noise level in a wide frequency range, despite that the sources due to turbulent flows are not modelled. In addition, the influence of these unsteady effects is observer angle-dependent, and the influences in the perpendicular directions are more significant than that on the rotational plane of the rotor. Similar observations are found for cases with oncoming flows in the axial direction. © 2022, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
Original languageEnglish
Publication statusPublished - 2022


  • Acoustic noise
  • Aeroacoustics
  • Aviation
  • Computation theory
  • Rotation
  • Aerodynamic noise
  • Blade vibrations
  • Fixed pitches
  • Parametric study
  • Rotation speed
  • Rotational speed
  • Rotor aerodynamics
  • Speed fluctuations
  • Speed variations
  • Unsteady motion
  • Cost effectiveness


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