Abstract:Wind energy is one of the fastest growing sources of sustainable energy production. As more wind turbines are coming into operation, the best locations are already becoming occupied by turbines, and wind-farm developers have to look for new and still available areas—locations that may not be ideal such as complex terrain landscapes. In these locations, turbulence and wind shear are higher, and in general wind conditions are harder to predict. Also, the modelling of the wakes behind the turbines is more complic… Show more
“…More than 70% of the Earth's land surface is in complex terrain (Strobach 1991), and thus mountain meteorology has attracted the attention of a wide range of constituencies, including climatologists (Gobiet et al 2014), fluid dynamists (Fernando 2010), and wind engineers (Alfredsson and Segalini 2017). Most past research has been on mesoscales (~1-100 km), spurred by air pollution, aviation, warfare, and energy applications.…”
mentioning
confidence: 99%
“…wind farms, especially in Europe, because complex terrain areas are readily found away from human settlements and available flat terrain suitable for wind energy production is at a premium (Alfredsson and Segalini 2017). Complex terrain offers the advantages of wind amplification at ridges, flow jetting through canyons, and remoteness from urban communities with strict noise regulations.…”
A grand challenge from the wind energy industry is to provide reliable forecasts on mountain winds several hours in advance at microscale (∼100 m) resolution. This requires better microscale wind-energy physics included in forecasting tools, for which field observations are imperative. While mesoscale (∼1 km) measurements abound, microscale processes are not monitored in practice nor do plentiful measurements exist at this scale. After a decade of preparation, a group of European and U.S. collaborators conducted a field campaign during 1 May–15 June 2017 in Vale Cobrão in central Portugal to delve into microscale processes in complex terrain. This valley is nestled within a parallel double ridge near the town of Perdigão with dominant wind climatology normal to the ridges, offering a nominally simple yet natural setting for fundamental studies. The dense instrument ensemble deployed covered a ∼4 km × 4 km swath horizontally and ∼10 km vertically, with measurement resolutions of tens of meters and seconds. Meteorological data were collected continuously, capturing multiscale flow interactions from synoptic to microscales, diurnal variability, thermal circulation, turbine wake and acoustics, waves, and turbulence. Particularly noteworthy are the extensiveness of the instrument array, space–time scales covered, use of leading-edge multiple-lidar technology alongside conventional tower and remote sensors, fruitful cross-Atlantic partnership, and adaptive management of the campaign. Preliminary data analysis uncovered interesting new phenomena. All data are being archived for public use.
“…More than 70% of the Earth's land surface is in complex terrain (Strobach 1991), and thus mountain meteorology has attracted the attention of a wide range of constituencies, including climatologists (Gobiet et al 2014), fluid dynamists (Fernando 2010), and wind engineers (Alfredsson and Segalini 2017). Most past research has been on mesoscales (~1-100 km), spurred by air pollution, aviation, warfare, and energy applications.…”
mentioning
confidence: 99%
“…wind farms, especially in Europe, because complex terrain areas are readily found away from human settlements and available flat terrain suitable for wind energy production is at a premium (Alfredsson and Segalini 2017). Complex terrain offers the advantages of wind amplification at ridges, flow jetting through canyons, and remoteness from urban communities with strict noise regulations.…”
A grand challenge from the wind energy industry is to provide reliable forecasts on mountain winds several hours in advance at microscale (∼100 m) resolution. This requires better microscale wind-energy physics included in forecasting tools, for which field observations are imperative. While mesoscale (∼1 km) measurements abound, microscale processes are not monitored in practice nor do plentiful measurements exist at this scale. After a decade of preparation, a group of European and U.S. collaborators conducted a field campaign during 1 May–15 June 2017 in Vale Cobrão in central Portugal to delve into microscale processes in complex terrain. This valley is nestled within a parallel double ridge near the town of Perdigão with dominant wind climatology normal to the ridges, offering a nominally simple yet natural setting for fundamental studies. The dense instrument ensemble deployed covered a ∼4 km × 4 km swath horizontally and ∼10 km vertically, with measurement resolutions of tens of meters and seconds. Meteorological data were collected continuously, capturing multiscale flow interactions from synoptic to microscales, diurnal variability, thermal circulation, turbine wake and acoustics, waves, and turbulence. Particularly noteworthy are the extensiveness of the instrument array, space–time scales covered, use of leading-edge multiple-lidar technology alongside conventional tower and remote sensors, fruitful cross-Atlantic partnership, and adaptive management of the campaign. Preliminary data analysis uncovered interesting new phenomena. All data are being archived for public use.
“…The main objective of this research is to perform a comprehensive CFD analysis in hilly terrain to optimize the siting of the turbines by considering their obstruction effect. While several studies have shown that complex terrain affects the wake flow of wind turbines [3][4][5], few research papers have focused on studying its effect on the velocity profile approaching the leading edge of the turbine, which may be an area for further research. Additionally, this work was carried out to assess the efficiency of the CFD model on the airflow distribution in the neutral atmospheric boundary layer (ABL) to describe the impact of topography in the micro-scale wind farms in open hilly terrain, which was considered by the implementation of four wind turbines aligned with two different hill slopes.…”
The performance of a wind turbine depends on the characteristics of the airflow as well as the conditions of the atmospheric boundary layer (ABL). To evaluate accurately the amount of wind energy, it is required to have the exact height distribution of wind speed for the considered implementation site of a wind turbine. In this paper, computational fluid dynamics (CFD) simulation predictions provided by the standard k-ε turbulence model under neutral conditions were examined. The objective is to investigate the influence of hill slopes in the microscale wind farm on the airflow velocity to optimize the location of wind turbines. The results were validated by RUSHIL wind tunnel data and were compared with flat terrain.
“…Although a lot of emphasis has been on understanding wakes in flat terrain over the past decade (Medici and Alfredsson, 2006;Jimenez et al, 2007;Chamorro and Porté-Agel, 2009;Iungo et al, 2013;Calaf et al, 2010;Porté-Agel et al, 2011;Abkar et al, 2016;Allaerts and Meyers, 2015;Iungo, 2016), complex terrains now finally get the attention they deserve. This is partly due to a prospective shift in development of wind farms from flat to complex terrains caused by saturation of ideal flat terrains and increasing development of wind energy over the past 2 decades (Alfredsson and Segalini, 2017;Feng et al, 2017); it is also partly due to the recent observational and numerical developments. Understanding wakes from turbines in complex terrains, therefore, becomes important for understanding the interaction between terrain and wakes, as well as for better resource assessment and wind farm siting.…”
Abstract. We perform large eddy simulation of flow in a complex terrain under neutral atmospheric stratification. We study the self-similar behavior of a turbine wake as a function of varying terrain complexity and perform comparisons with a flat terrain. By plotting normalized velocity deficit profiles in different complex terrain cases, we verify that self-similarity is preserved as we move downstream from the turbine. We find that this preservation is valid for a shorter distance downstream compared to what is observed in a flat terrain. A larger spread of the profiles toward the tails due to varying levels of shear is also observed.
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