Numerical prediction of wind turbine noise using large eddy simulation

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Among the various sources of energy, wind energy represents a cleaner and more sustainable source of energy than those derived from either coal or fissile nuclear materials. Wind power is renewable and friendly to the surrounding environment (i.e., an "answer" to climate change and local/regional air pollution). However, the main disadvantage regarding wind power is its unreliability (viz., the wind is not always present with enough velocity to power a wind energy system) and noise pollution. In fact, the health effects arising from wind turbine noise are the source of much controversy. Setbacks for noise (defined as minimum horizontal separation distances between the base of a turbine and a noise receptor) are difficult to determine, because they are subjective rather than risk-based. It is against this background that a research program is put forward, in which advanced Computational Fluid Dynamics (CFD) algorithms based on a new adaptive mesh refinement (AMR) technique in conjunction with Large Eddy Simulation (LES) turbulence models will be developed. The LES solutions will be used to compute the thickness (monopole), loading (dipole) and quadrupole noise source terms in the Ffowcs, William and Hawkings (FWH) equation in order to predict far-field noise. To validate our numerical procedure, acoustic data (e.g., sound pressure level (SPL) vs. frequency) from cooling fan(s) and/or (scaled model) wind turbine(s) in different configurations (e.g., stand-alone, in serial and in parallel) will be measured in an anechoic chamber in the Energy Research Center at the University of Waterloo. This anechoic chamber requires refurbishment, and an accompanying NSERC RTI proposal will be submitted to acquire new acoustical foam, a data acquisition system, microphones and other accessories required to support the experimental program. The outcome of this proposal will be used to assist health researchers in answering questions such as what are the physiological effects (anxiety, tinnitus or hearing loss) of wind turbine noise.