Abstract
Using the method based on unmanned aerial vehicle (UAV) imagery, two kinds of data can be obtained: the digital elevation model (DEM) for the digital expression of terrain, and the digital surface model (DSM) for the digital expression of the surface of the ground, including trees. In this research, a 3D topography model with a horizontal spatial resolution of 1 m was reproduced using DEM. In addition, using the differences between the DEM and DSM data, we were able to obtain further detailed information, such as the heights of trees covering the surface of the ground and their spatial distribution. Therefore, the surface roughness model and the UAV imagery data were directly linked. Based on the above data as input data, a high-resolution 3D numerical flow simulation was conducted. By using the numerical results obtained, we discussed the effect of the existence of surface roughness on the wind speed at the height of the hub of the wind turbine. We also discussed the effect of the differences in the spatial resolution in the horizontal direction of the computational grid on the reproductive precision of terrain-induced turbulence. As a result, the existence and the vortex structure of terrain-induced turbulence occurring near the target wind turbine was clearly revealed. It was shown that a horizontal grid resolution of about 5 m was required to reproduce terrain-induced turbulence formed from topography with an altitude of about 127 m. By the simulation using the surface roughness model, turbulence intensity higher than class A in the International Electrotechnical Commission (IEC) turbulence category was confirmed at the present study site, as well as the measured data.
Highlights
Wind turbines are generally designed in compliance with power laws, in which wind speed gradually increases vertically upward and flows along the blades of the turbine
To reproduce invisible and complicated three-dimensional (3D) airflow structures that occur in the neighborhood of the wind turbines and visually grasp its flow and pattern, an approach based on computational fluid dynamics (CFD), such as Reynolds-Averaged Navier–Stokes (RANS) turbulence models and large-eddy simulation (LES) turbulence models, is useful [1,2,3,4,5,6,7,8,9,10]
In this research, we reproduced the target wind turbine site using a 3D topography model constructed by photographs taken from an unmanned aerial vehicle (UAV, commonly model constructed by photographs taken from an unmanned aerial vehicle (UAV, commonly known as known as a drone) with a spatial resolution of 1 m in the horizontal direction [15,16] and, by using a drone) with a spatial resolution of 1 m in the horizontal direction [15,16] and, by using it as input data it as input data into an LES turbulent model, we conducted a high-resolution 3D numerical flow into an LES turbulent model, we conducted a high-resolution 3D numerical flow simulation
Summary
Wind turbines are generally designed in compliance with power laws, in which wind speed gradually increases vertically upward and flows along the blades of the turbine. To12,precisely reproduce the terrain-induced turbulence on a computer via numerical simulation of the wind conditions, accurately reproducing the terrain condition on site is crucial, including the degrees of ups and downs, the heights of trees covering the surface of terrain, and wind conditions, accurately reproducing the terrain condition on site is crucial, including the degrees their spatial distribution. In this research, we reproduced the target wind turbine site using a 3D topography model constructed by photographs taken from an unmanned aerial vehicle (UAV, commonly model constructed by photographs taken from an unmanned aerial vehicle (UAV, commonly known as known as a drone) with a spatial resolution of 1 m in the horizontal direction [15,16] and, by using a drone) with a spatial resolution of 1 m in the horizontal direction [15,16] and, by using it as input data it as input data into an LES turbulent model, we conducted a high-resolution 3D numerical flow into an LES turbulent model, we conducted a high-resolution 3D numerical flow simulation. Methods were verified [13]
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