Experimental investigation of turbulent coherent structures interacting with a porous airfoil

Journal article (2021)

Authors

Simone Tamaro von Karman Institute for Fluid Dynamics
R. Zamponi von Karman Institute for Fluid Dynamics
D. Ragni Wind Energy - Aerospace Engineering
C. Teruna Wind Energy - Aerospace Engineering
Christophe Schram von Karman Institute for Fluid Dynamics
Research Group
Wind Energy (Aerospace Engineering) (TU Delft)
Copyright: © 2021 Simone Tamaro, R. Zamponi, D. Ragni, C. Teruna, Christophe Schram
DOI
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https://doi.org/10.1007/s00348-021-03170-2
Aeroacoustics POD Porous materials Turbulence-interaction noise
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Published Date

2021

Language

English

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Faculty

Aerospace Engineering

Department

Flow Physics and Technology

Research Group

Wind Energy

Abstract

Abstract: The flow field on solid and porous airfoils subjected to turbulence shed by an upstream cylindrical rod and the corresponding far-field noise radiations are studied through particle image velocimetry (PIV) and microphone measurements, respectively. Three different Reynolds numbers based on the rod diameter are considered in a range between 2.7 × 10
4 and 5.4 × 10
4, and two porous airfoil models are tested to analyze the influence of the design elements of the permeable treatment. A standard proper orthogonal decomposition (POD) algorithm is employed to band filter the different length scales that characterize the turbulent flow, making it feasible to determine which turbulence scales are affected by porosity. The aeroacoustic results indicate that the porous treatment of the wing profile leads to a noise reduction at low frequencies and a noise regeneration at high frequencies due to surface roughness. The investigation on the flow field shows that the main effect of porosity is to mitigate the turbulent kinetic energy in the stagnation region, attenuating the distortion of turbulence interacting with the airfoil surface. The application of the POD algorithm indicates that this effect acts mainly on the largest scales of turbulence. Graphic abstract: [Figure not available: see fulltext.].