NACA0018の風洞試験に基づく水平軸風車の乱流境界層から発生する広帯域騒音の予測NACA0018の風洞試験に基づく水平軸風車の乱流境界層から発生する広帯域騒音の予測 Prediction of Broadband Noise Generated from Turbulent Boundary Layers of a Horizontal Axis Wind Turbine Based on Wind Tunnel Test of NACA0018
We expanded the blade element momentum theory (BEM) for the prediction of the broadband noise of a horizontal axis wind turbine. For the prediction of the broadband noise, the acoustic radiation from the turbulent boundary layers was applied. From the results of the wind tunnel test, NACA0018 generated the humped noise in the attached flow condition, whereas the noise spectra in the separated flow condition made the broadband noise. In this prediction methodology, the noise level of the wind turbine could be predicted by the model size of the isolated blade and the main dimensions of the objective wind turbine. At this time, the relative velocity and the angle of attack became the important parameters. We pointed out that the humped noise source in the wind turbine was made from the mid-span to the blade tip on the impeller based on this methodology.