Turbulent Inflow Noise Analysis

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a. Turbulent Inflow Noise
As mentioned previously, the inflow noise is caused by the interaction of the turbulent air with the blade as the turbulent atmosphere cause a fluctuating pressure on the blade which leads to noise radiation. This noise source is a dominant source to the overall wind turbine noise.
The intensity of the air turbulence can be varied according to the different temperature gradient and the interaction with the ground surface, which results in air masses rotation and producing turbulent eddies. The different sizes of eddies interact with the blade producing low or high frequencies depending on their relative sizes. The low frequency is caused when the eddy size is larger than the segment chord length, and vice versa. That is why the turbulent inflow noise is a broadband noise.
Equation (1-12) is the main formula for the high frequency levels which will be corrected in equation (1-13) for the low frequency ranges. (1-12) (1-13)
b. Trailing-Edge Noise.
This prediction code is a re-analysis of the measured data of BPM model. (1-14) Grosveld's Model [4]
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The noise model predicts the emitted noise levels based on some parameters definition and the sound level definition of the noise sources existing inside the project boarder. This study has to be implemented before the construction phase to know the negative effects of the project before the installation phase in order to be able to take the appropriate decision. Windfarms have to be considered as industrial noise emitters which have to be studied to know their effect on the surroundings. The noise prediction model assumes that the windfarm consists of point sources located at the hub height of the wind turbines. This assumption is valid in case the distance between the nearest receiver and the wind turbine is 2.5 times the rotor diameter or

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