Effects of wind turbine wake on atmospheric sound propagation

Abstract In this paper, we investigate the sound propagation from a wind turbine considering the effects of wake-induced velocity deficit and turbulence. In order to address this issue, an advanced approach was developed in which both scalar and vector parabolic equations in two dimensions are solved. Flow field input was obtained using the actuator line (AL) technique with Large Eddy Simulation (LES) to model the wind turbine and its wake and from an analytical wake model. The effect of incoming wind speed and atmospheric stability was investigated with the analytical wake input using a single point source. Unsteady acoustic simulations were carried out with the AL/LES input for three cases with different incoming turbulence intensity, and a moving source approach to mimic the rotating turbine blades. The results show a non-negligible effect of the wake on far-field noise prediction. Particularly under stable atmospheric conditions, SPL amplification reaches up to 7.5 dB at the wake centre. Furthermore, it was observed that when the turbulence intensity level of the incoming flow is higher, the SPL difference between the moving and the steady source is lower.

[1]  Seongkyu Lee,et al.  Prediction of far-field wind turbine noise propagation with parabolic equation. , 2016, The Journal of the Acoustical Society of America.

[2]  P. Blanc-Benon,et al.  Derivation of a wide-angle parabolic equation for sound waves in inhomogeneous moving media , 2013 .

[3]  Stefan Ivanell,et al.  Simulation of wind turbine wakes using the actuator line technique , 2015, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[4]  Philippe Blanc-Benon,et al.  A WIDE-ANGLE PARABOLIC EQUATION FOR ACOUSTIC WAVES IN INHOMOGENEOUS MOVING MEDIA: APPLICATIONS TO ATMOSPHERIC SOUND PROPAGATION , 2001 .

[5]  E. N. Bazley,et al.  Acoustical properties of fibrous absorbent materials , 1970 .

[6]  Pieter Sijtsma,et al.  Nationaal Lucht-en Ruimtevaartlaboratorium National Aerospace Laboratory NLR NLR-TP-2007-798 Location and quantification of noise sources on a wind turbine , 2008 .

[7]  Jens Nørkær Sørensen,et al.  Numerical Modeling of Wind Turbine Wakes , 2002 .

[8]  Yvonne Käsler,et al.  The wake of a wind turbine and its influence on sound propagation , 2011 .

[9]  Jens Nørkær Sørensen,et al.  Modeling of Aerodynamically Generated Noise From Wind Turbines , 2005 .

[10]  Niels N. Sørensen,et al.  The DAN-AERO MW Experiments , 2010 .

[11]  Niels N. Sørensen,et al.  General purpose flow solver applied to flow over hills , 1995 .

[12]  F. Porté-Agel,et al.  A new analytical model for wind-turbine wakes , 2013 .

[13]  Mark A. Coleman,et al.  Sound Propagation in the Nocturnal Boundary Layer , 2003 .

[14]  M. West,et al.  A tutorial on the parabolic equation (PE) model used for long range sound propagation in the atmosphere , 1992 .

[15]  P. Blanc-Benon,et al.  Estimates of the relevant turbulent scales for acoustic propagation in an upward refracting atmosphere , 2007 .

[16]  S. Gryning,et al.  Long-Term Mean Wind Profiles Based on Similarity Theory , 2010 .

[17]  E. Salomons.  Computational Atmospheric Acoustics , 2001 .

[18]  L. Dallois.  Long Range Sound Propagation in a Turbulent Atmosphere Within the Parabolic Approximation , 2001 .

[19]  J. Mann.  Wind field simulation , 1998 .

[20]  Fernando Porté-Agel,et al.  The effect of atmospheric stability on wind-turbine wakes: A large-eddy simulation study , 2014 .