Vertical Axis Wind Turbines (VAWT) have the potential to be installed nearby urban areas, where noise regulations are a constraint. To account for noise regulation already in the design phase, modelling of the noise sources is necessary. For a correct prediction of the far-field noise, the flow over the blades and the near wake of a VAWT need to be accurately modelled to provide the correct inputs to the noise prediction models [1, 2]. Since in the literature, there is not consensus on how to obtain these inputs parameters, high fidelity simulations of a realistic 1.5m 2-bladed H-Darrieus VAWT at tip-speed ratio of 4, for which aerodynamic reference data are available [3], are carried out with the lattice-Boltzmann Very Large Eddy software SIMULIA PowerFLOW. The resulting dataset, which links the far-field noise with the unsteady aerodynamics, is used as a benchmark for a low-fidelity model. The latter retrieves flow parameters using the Actuator Cylinder model [4], where the boundary layer integral parameters are determined with Xfoil. These inputs are then used to predict airfoil self-noise and turbulence impingement noise [1, 5]. Preliminary results show a good agreement between high-fidelity simulations and low-fidelity model at low frequencies, where turbulence-impingement noise is the most dominant noise source. At higher frequencies, laminar boundary layer–vortex shedding noise is the dominant source because of the low Reynolds number flow. For this noise source, a small disagreement between the high-fidelity and the low-fidelity results exists for the frequency of maximum noise. This might be caused by the presence of the struts, which largely affect the velocity perceived by the blades. 

References

[1] Botha, Trinity College Dublin Ireland, (2018).

[2] Pearson, Corpus Christi College Cambridge University, (2013).

[3] LeBlanc and Ferreira, 2018 Wind Energy Symposium, 1, (2018).

[4] H. A. Madsen, The Actuator Cylinder - A Flow Model for Vertical Axis Wind Turbines, (1982).

[5] T. F. Brooks, S. Pope, and M. A. Marcolini, Airfoil Self-Noise and Prediction, (1989).