Validity of Amiet’s Theory on Airfoil Wall-Pressure Fluctuations Subjected to Turbulent Inflow
conference paper
A turbulent inflow induces wall-pressure fluctuations (WPFs) on a foil surface, causing hydro/aeroacoustic and vibroacoustic noise. Amiet’s theory, derived for a thin flat plate, can be used to predict these pressure fluctuations. However, the turbulent inflow distorts as it approaches the foil leading edge, which affects them WPF but which is not considered in Amiet’s theory. This paper aims to analyze the validity of Amiet’s prediction for the WPFs for airfoils and to investigate the effect of turbulence distortion on the WPFs and the prediction. Experiments were performed with NACA 0008 and NACA 63018 airfoils, subjected to a grid-generated turbulent inflow. The WPFs were measured along the chord and span for effective angles of attack 0◦–6.2◦. The experimental results show that the WPF spectrum is affected by the turbulence distortion in the first 5% of the chord length, resulting in lower spectral levels than the prediction. An improvement to the prediction for these locations can be made by using as input to Amiet’s model the value for the turbulence length scale measured close to the leading edge. Amiet’s prediction using the free-stream value for the length scale matches well with the measurements for chordwise positions downstream of 10% of the chord length since the turbulence distortion effect is negligible for these positions. The comparison between measured and predicted WPF at high frequencies becomes worse at larger chordwise positions because the WPFs induced by the turbulent boundary layer become noticeable in the experiments.
TNO Identifier
1006322
ISBN
978-3-031-73935-4
Publisher
Springer
Source title
Flinovia—Flow Induced Noise and Vibration Issues and Aspects—IV
Editor(s)
Doolan, C.
Moreau, D.
Wills, A.
Moreau, D.
Wills, A.
Place of publication
Cham
Pages
55-86
Files
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