Abstract
Airfoil turbulence interaction noise and the flow field up to and over the porous leading edge is experimentally studied. The porous leading edges were of the same base triply periodic minimal surface structure with varying porosity to enable us to understand how the porosity, permeability, and pore size affect the generated turbulence interaction noise. The turbulent flow was generated by means of a passive turbulence grid that does not affect the normal background noise of the wind tunnel. Far-field noise results were obtained from a polar microphone array to assess the directivity of the sound as well as the narrowband frequency contributions. Far-field noise results demonstrate
that increasing porosity reduces the turbulence interaction noise over low-to-mid frequencies, with a penalty of a high frequency noise increase. Flow measurement results indicate hydrodynamic penetration of the flow into the
porous structure at the leading edge. Furthermore, the two-point correlation analysis of the velocity fluctuations approaching the leading edge shows that the turbulent structures approaching the solid leading edge appear to deform into more two-dimensional structures, whereas in the case of the porous leading edge, the turbulent structures appear to retain a strong spanwise coherence up to the point of hydrodynamic penetration.
that increasing porosity reduces the turbulence interaction noise over low-to-mid frequencies, with a penalty of a high frequency noise increase. Flow measurement results indicate hydrodynamic penetration of the flow into the
porous structure at the leading edge. Furthermore, the two-point correlation analysis of the velocity fluctuations approaching the leading edge shows that the turbulent structures approaching the solid leading edge appear to deform into more two-dimensional structures, whereas in the case of the porous leading edge, the turbulent structures appear to retain a strong spanwise coherence up to the point of hydrodynamic penetration.
| Original language | English |
|---|---|
| Pages (from-to) | 1437-1448 |
| Number of pages | 12 |
| Journal | Journal of the Acoustical Society of America |
| Volume | 152 |
| Issue number | 3 |
| Early online date | 6 Sept 2022 |
| DOIs | |
| Publication status | Published - 6 Sept 2022 |
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 1/12/2022. All authors would like to acknowledge the financial support of EPSRC via Grant No. EP/S013024/1.
Publisher Copyright:
© 2022 Acoustical Society of America.
Keywords
- Aeroacoustics
- aerodynamics
- Porous materials
- Turbulence interaction noise
- airfoil noise
- grid generated turbulence
- triply period minimal surfaces