Sound propagation from a ridge wind turbine across a valley

Abstract

SummarySound propagation outdoors can be strongly affected by ground topography. The existence of hills and valleys between a source and receiver can lead to the shielding or focussing of sound waves. Such effects can result in significant variations in received sound levels. In addition, wind speed and air temperature gradients in the atmospheric boundary layer also play an important role. All of the foregoing factors can become especially important for the case of wind turbines located on a ridge overlooking a valley. Ridges are often selected for wind turbines in order to increase their energy capture potential through the wind speed up effects often experienced in such locations. In this paper, a hybrid calculation method is presented to model such a case, relying on an analytical solution for sound diffraction around an impedance cylinder and the conformal mapping (CM) Green's Function Parabolic Equation (GFPE) technique. The various aspects of the model have been successfully validated against alternative prediction methods. Example calculations with this hybrid analytical-CM-GFPE model show the complex sound pressure level distribution across the valley and the effect of valley ground type. The proposed method has the potential to include the effect of refraction through the inclusion of complex wind and temperature fields, although this aspect has been highly simplified in the current simulations.

Sound propagation through the wake flow of a hilltop wind turbine—A numerical study

“…Besides measurements, they used a ray model, but horizontal variations of the wind were not accounted for. Most recently, Van Renterghem has used a hybrid method with analytical solutions in combination with a parabolic equation model to simulate the sound propagation from a ridge‐top wind turbine across a valley. However, effects of the hill and the turbine on the atmosphere have not been considered in this study.…”

Introduction Wind farms in complex terrains: an introduction

“…This introduction gives an overview of the current status of fluid-dynamics research areas that relate to flow over complex terrain and also introduces the papers that are included in this theme issue. The topics include wind statistics on both the micro-and macro-scale level [2], the effect of surface roughness on the description of boundary-layer flow physics [3,4], the effect of complex terrain on sound propagation [5], as well as various strategies for modelling the flow field around wind turbines [6][7][8] and wind farms [9][10][11].…”

“…This implies that caution must be used when analysing field experimental data, especially from measurements in complex terrains. Sound propagation [5] can be investigated after characterization of the velocity field. Here, the terrain roughness and topology, as well as the incoming boundary layer, in terms of both its velocity distribution and turbulence, are importance parameters.…”

“…This theme issue of the Philosophical Transactions of the Royal Society A mainly builds on presentations [2][3][4][5][6][7][8][9][10][11] made at the EUROMECH Colloquium 576, Wind Farms in Complex Terrain, which took place at KTH Royal Institute of Technology in Stockholm, Sweden, over 3 days in June 2016. The main focus of the Colloquium was the various issues related to complex terrains, mainly from the aerodynamic, meteorological and noise-propagation points of view.…”

“…The topics include wind statistics on both the micro-and macro-scale level [2], the effect of surface roughness on the description of boundary-layer flow physics [3,4], the effect of complex terrain on sound propagation [5], as well as various strategies for modelling the flow field around wind turbines [6][7][8] and wind farms [9][10][11].…”