Validations and Improvements of Airfoil Trailing-edge Noise Prediction Models Using Detailed Experimental Data
M. Kamruzzaman, Th. Lutz, W. Würz, W. Shen, W. Zhu, M. O. L. Hansen, F. Bertagnolio and H. Aa. Madsen, published in online at Wind Energy, DOI: 10.1002/we.505, November 2011
This paper describes an extensive assessment and a step by step validation of different turbulent boundary-layer trailing-edge noise prediction schemes developed within the European Union funded wind energy project UpWind. To validate prediction models, measurements of turbulent boundary-layer properties such as two-point turbulent velocity correlations, the spectra of the associated wall pressure fluctuations and the emitted trailing-edge far-field noise were performed in the laminar wind tunnel of the Institute of Aerodynamics and Gas Dynamics, University of Stuttgart. The measurements were carried out for a NACA 643-418 airfoil, at Re = 2.5 ×106, angle of attack of −6° to 6°. Numerical results of different prediction schemes are extensively validated and discussed elaborately. The investigations on the TNO-Blake noise prediction model show that the numerical wall pressure fluctuation and far-field radiated noise models capture well the measured peak amplitude level as well as the peak position if the turbulence noise source parameters are estimated properly including turbulence anisotropy effects. Large eddy simulation based computational aeroacoustic computations show good agreements with measurements in the frequency region higher than 1 kHz, whereas they over-predict the sound pressure level in the low-frequency region.