| The impact of acoustics of wind turbine on the environment has become increasingly prominent, gaining widespread concern in recent years. The investigations of wind turbine blade acoustics are importance to reduce this impact. With the increase in computing power and improved calculation method, numerical simulations have become the primary means of wind turbine acoustics research. In this paper, Fluent software is employed to simulate a straight Wade based on NACA0012 airfoil. Different flow conditions of different angles of attack and different trailing edge thickness are simulated. The flow field around blade are analyzed, as well as the flow structures of the blade trailing edge region and wake flow field. Based on the results of CFD calculations, FW-H method and the FFT transform are performed to get the sound field distribution of the blade acoustics. The acoustic variations and attenuation for the monitoring points are obtained. The following conclusions can be drawn:(1) Blade trailing edge region has the largest pressure pulsation, which indicateds the trailing edge is a major source of the blade acoustics.(2) When the angle of attack is small, the monitoring points will be significant peak of sound pressure level, the discrete nature of acoustics is more obvious. When the angle of attack is greater than the six degree, the sound pressure level has not a significant peak. So with the angle of attack increases, the discrete noise will gradually disappear, the noise spectrum mainly reflects the broadband noise. Moreover, with the angle of attack increases, the low-frequency noise reducesgradually, while the high-frequency noise increases.(3) On the small angle of attack, the clocked frequency in the low frequency band is consistent with the frequency of trailing edge vortex shedding. This means that the trailing edge vortex shedding is a major factor to cause the low frequency sound pressure level appearing a peak.(4) In the case of a certain angle of attack, with increasing of the trailing edge, the sound pressures of both the discrete noise in the low frequency and high frequency increase. Therefore, the greater the thickness of the trailing edge, the larger acoustics for wind turbine blade will be. |
