Wind turbine noise prediction with high-fidelity flow simulations

What is it about?

Numerical tools, and especially computational fluid dynamics (CFD), are becoming increasingly important in the design stage to enable multi-fidelity optimization of next generation wind turbine platforms. In addition to pure aerodynamics prediction, studying the emitted noise levels is of growing interest to the industry, since wind turbines are steadily increasing in size as well as moving closer to urban areas. Assessing novel simulation approaches is therefore instrumental for replacing / complementing costly experimental campaigns as well as for gaining a more detailed insight into the physical noise generation mechanisms. In the paper, we compare different flow simulation approaches from Upstream CFD (innovative SME from Berlin / Germany specialized in consulting for high-fidelity CFD) and ENERCON (German-based wind turbine manufacturer) with comprehensive experimental data produced by the German Aerospace Center (DLR). The capabilities of the applied simulation methods to correctly predict both aerodynamic characteristics as well as noise are carefully evaluated for a wind turbine airfoil with blunt trailing edge. It is found that it is crucial to accurately capture the near wall flow by resolving turbulent eddies in this region for predicting both the narrow-band shedding tone as well as the broadband part of the radiated acoustics. Such turbulence-resolving simulation approaches, which are not yet routinely applied in industry due to their high computational costs, will become increasingly important in the future due to their superior physical accuracy relative to more empirical-based methods currently in use.

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Photo by Waldemar Brandt on Unsplash

Photo by Waldemar Brandt on Unsplash

Why is it important?

For many technical applications, the prediction of noise levels with computed-aided methods has become increasingly important to better study and develop optimized products. This is also true for wind turbines, where reducing the noise print of wind farms is a major design goal to reduce the disturbance of nearby residents as well as the fauna. For this purpose, highly accurate simulation methods are required, which have to be thoroughly validated against experimental reference data before being integrated into the industrial design process.