Acoustic tomography of turbulent flows near wind turbines

Acoustic tomography of the atmosphere is a relatively unexplored remote sensing technology with the potential to improve fundamental scientific knowledge of atmospheric turbulence and acoustic wave propagation in the atmosphere and potential to expand our capabilities in terms of wind turbine wake observations. Existing remote sensing technologies rely on wave backscatter off of airborne particulate matter, which limits spatial and temporal resolution and cannot produce reliable flow estimates near solid bodies. In contrast, acoustic tomography relies on the direct travel of signals between transducers in a network and can achieve much higher resolutions in space and time. Signal travel times are combined using a stochastic inversion technique to reconstruct both the velocity and temperature fields within the transducer network. An acoustic tomography array at the National Wind Technology Center has been developed to investigate atmospheric flows from which energy is extracted by utility scale wind turbines and to make observations around wind turbines to illuminate wake physics and provide highly resolved observations necessary for high-fidelity model validation efforts.