A thorough experimental investigation on airfoil turbulence interaction noise

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7 Citations (Scopus)

Abstract

This paper on aerofoil turbulence interaction noise reveals the nature of the relation between the distortion type of turbulent structures and radiated far-field noise. The turbulence interaction phenomenon is explored through comprehensive simultaneous hot-wire, surface pressure and far-field noise measurements. Two grid turbulence cases are utilized to examine the effect of the coherent structure's length scale compared to the aerofoil's leading-edge radius. The results show that the turbulent structures with a size comparable to the leading-edge radius disperse into smaller three-dimensional structures, losing their spatial coherence in the vicinity of the stagnation point. In contrast, the structures with larger integral length scales distort into highly-coherent two-dimensional structures, yielding an increase in the surface pressure fluctuation energy spectra and the chordwise extent of the affected area by the interaction phenomenon, which is found to be responsible for the increased levels of far-field noise. The turbulence characteristics of the flow far upstream of the stagnation point determine the unsteady loading behaviour at the stagnation point yet have little influence on the unsteady loading of the full aerofoil chord. The stagnation point velocity fluctuations manifest a strong link to the remainder of the aerofoil chord, as well as the near-field hydrodynamic to far-field acoustic signal coherence, whilst demonstrating no communication with the surface pressure fluctuations at the stagnation point.
Original languageEnglish
Article number035123
JournalPhysics of Fluids
Volume35
Issue number3
Early online date16 Mar 2023
DOIs
Publication statusE-pub ahead of print - 16 Mar 2023

Bibliographical note

Funding Information:
The first author (L.B.) would like to acknowledge the financial support of Embraer S.A. and an Engineering and Physical Sciences Research Council doctoral training partnership (EPSRC DTP). The second author (A.C.) was sponsored by EPSRC via Grant No. EP/S013024/1 at the University of Bristol from 1/6/2020 to 1/12/2021. All authors would like to acknowledge the financial support of EPSRC via Grant No. EP/S013024/1.

Publisher Copyright:
© 2023 Author(s).

Keywords

  • aeroacoustics
  • turbulence
  • turbulence interaction noise
  • aerofoil
  • aerofoil turbulence interaction

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