An experimental study of aerodynamic noise from large obstructions in turbulent boundary layer flows

Shivam Sundeep, Huanxian Bu, Peng Zhou, Siyang Zhong, Xin Zhang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

This paper reports an experimental study on the aerodynamic noise generated by a two-dimensional large obstacle in a turbulent boundary layer. Square and triangular obstacles with varying heights of h / δ = 0.48, 0.8, 1.2, 1.6, and 2 (where δ is the boundary layer thickness measured without the obstacle present) are tested at various flow speeds ranging from 20 to 50 m/s. The Reynolds number based on step height and free stream velocity ranged between 7500 and 79 000. A linear microphone array is arranged aside to measure the sound radiation in the spanwise direction. It is suggested that both square and triangular obstructions can lead to a broadband source with a dipole-type directivity. A consistent increase in the noise strength is observed with obstacle height and flow speed. The underlying noise source is revealed by comparing the acoustic spectra of different obstacle geometries. The low-frequency noise is contributed by the turbulence modification due to the flow impingement onto the obstacle, while the high-frequency sound is mainly caused by the diffraction of hydrodynamic pressure by the sharp leading edge. © 2022 Author(s).
Original languageEnglish
JournalPhysics of Fluids
Volume34
Issue number2
DOIs
Publication statusPublished - 2022

Keywords

  • Acoustic noise
  • Aerodynamics
  • Atmospheric thermodynamics
  • Boundary layer flow
  • Boundary layers
  • Turbulence
  • Turbulent flow
  • Aerodynamic noise
  • Boundary layer thickness
  • Flow speed
  • Freestream velocity
  • Linear microphonearray
  • Reynold number
  • Step-height
  • Turbulent boundary layer flow
  • Turbulent boundary layers
  • Two-dimensional
  • Reynolds number

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