Measurement of atmospheric boundary layer based on super-large-scale particle image velocimetry using natural snowfall

Toloui, Mostafa; Riley, Sean; Hong, Jiarong; Howard, Kevin; Chamorro, Leonardo P.; Guala, Michele; Tucker, James R.

doi:10.1007/s00348-014-1737-1

Cited by 46 publications

(61 citation statements)

References 42 publications

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“…Using the meteorological tower near the 2.5 MW Eolos turbine in Rosemount, Minnesota (details in Toloui et al 2014;Hong et al 2014), on May 6 2014, we detected a clear transition in the thermal regime from stable (S) to neutral (N) and weakly convective (C), see Fig. 4.…”

Section: Comparable Thermal-specific Mean Shear In the Atmospheric Sumentioning

confidence: 94%

A Comparative Analysis on the Response of a Wind-Turbine Model to Atmospheric and Terrain Effects

Howard

Chamorro

Guala

2015

Boundary-Layer Meteorol

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In a series of wind-tunnel experiments conducted at the St. Anthony Falls Laboratory, a wind-turbine model was exposed to three different thermal regimes (neutral, weakly stable and weakly convective flows) in three simple arrangements relevant to wind-farm applications: single turbine in the boundary-layer, aligned turbine-turbine, and an upwind three-dimensional sinusoidal hill aligned with the turbine. Results focus on the spatial evolution of large-scale motions developing over the different thermal and topographic boundary conditions, and on their influence on the mean and fluctuating angular velocity of the turbine rotor. As compared to the single turbine case, both the upwind hill and turbine caused a reduction in the mean angular velocity regardless of the thermal regime; the turbine angular velocity fluctuations always decreased with a turbine upwind, which depleted the energy of the large structures of the flow; however such fluctuations decreased (increased) under stably stratified (convective) conditions when the hill was present. Pre-multiplied spectra of the rotor angular velocity and two-point correlation contours of the streamwise velocity component confirmed a non-trivial link between thermal stratification and terrain complexity. It is inferred that the thermal effects occurring in the three different boundary-layer regimes modulate the spanwise motion of the hill wake and define whether the hill shelters or exposes the turbine to enhanced large-scale energetic motions.

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Section: Comparable Thermal-specific Mean Shear In the Atmospheric Sumentioning

confidence: 94%

A Comparative Analysis on the Response of a Wind-Turbine Model to Atmospheric and Terrain Effects

Howard

Chamorro

Guala

2015

Boundary-Layer Meteorol

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“…More detailed discussions of snowflake traceability are provided in in Supplementary Methods, including a comparison with a PIV tracer commonly used in the laboratory experiments such as olive oil droplets. Nevertheless, due to the complex and variable structure of snowflakes, we mainly rely on prior research 30 and our validation experiment (Toloui et al 35 , briefly summarized in the following section and in Supplementary Methods) to assess the quality of the measured velocity field using snowflake tracers.…”

Section: Methodsmentioning

confidence: 99%

“…The convergence error for mean velocity profile calculation is B0.027 ms À 1 . The measurement approach using the described experimental setup was validated through a separate set of study that focused on turbulent flow measurements in the ABL 35 . In this validation campaign, the SLPIV system was deployed in close proximity to the met tower at the Eolos wind energy research station, measuring turbulent flows in sampling area of B22 m Â 52 m, up to B56 m above the ground.…”

Section: Methodsmentioning

confidence: 99%

Natural snowfall reveals large-scale flow structures in the wake of a 2.5-MW wind turbine

et al. 2014

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To improve power production and structural reliability of wind turbines, there is a pressing need to understand how turbines interact with the atmospheric boundary layer. However, experimental techniques capable of quantifying or even qualitatively visualizing the large-scale turbulent flow structures around full-scale turbines do not exist today. Here we use snowflakes from a winter snowstorm as flow tracers to obtain velocity fields downwind of a 2.5-MW wind turbine in a sampling area of B36 Â 36 m 2 . The spatial and temporal resolutions of the measurements are sufficiently high to quantify the evolution of bladegenerated coherent motions, such as the tip and trailing sheet vortices, identify their instability mechanisms and correlate them with turbine operation, control and performance. Our experiment provides an unprecedented in situ characterization of flow structures around utility-scale turbines, and yields significant insights into the Reynolds number similarity issues presented in wind energy applications.

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“…The sonic and lidar measurements are also used under undisturbed inflow conditions to develop an empirical correction against contamination in lidar turbulence measurements. In the Eolos site, the upwind inflow conditions resemble the canonical rough wall boundary layer . The lidar measurements in the second field location are inferred to be representative of a wind power plant, with inflow conditions potentially affected by upwind turbine wake meandering.…”

Section: Introductionmentioning

confidence: 99%

“…In the Eolos site, the upwind inflow conditions resemble the canonical rough wall boundary layer. 15 The lidar measurements in the second field location are inferred to be representative of a wind power plant, with inflow conditions potentially affected by upwind turbine wake meandering. In this respect, the current investigation aims at identifying the intensity and periodicity of wake meandering under a range of inflow conditions, operating turbine regimes, and weak thermal stability conditions and compare them with literature results.…”

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confidence: 99%

The spectral signature of wind turbine wake meandering: A wind tunnel and field‐scale study

2018

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Field‐scale and wind tunnel experiments were conducted in the 2D to 6D turbine wake region to investigate the effect of geometric and Reynolds number scaling on wake meandering. Five field deployments took place: 4 in the wake of a single 2.5‐MW wind turbine and 1 at a wind farm with numerous 2‐MW turbines. The experiments occurred under near‐neutral thermal conditions. Ground‐based lidar was used to measure wake velocities, and a vertical array of met‐mounted sonic anemometers were used to characterize inflow conditions. Laboratory tests were conducted in an atmospheric boundary layer wind tunnel for comparison with the field results. Treatment of the low‐resolution lidar measurements is discussed, including an empirical correction to velocity spectra using colocated lidar and sonic anemometer. Spectral analysis on the laboratory‐ and utility‐scale measurements confirms a meandering frequency that scales with the Strouhal number St = fD/U based on the turbine rotor diameter D. The scaling indicates the importance of the rotor‐scaled annular shear layer to the dynamics of meandering at the field scale, which is consistent with findings of previous wind tunnel and computational studies. The field and tunnel spectra also reveal a deficit in large‐scale turbulent energy, signaling a sheltering effect of the turbine, which blocks or deflects the largest flow scales of the incoming flow. Two different mechanisms for wake meandering—large scales of the incoming flow and shear instabilities at relatively smaller scales—are discussed and inferred to be related to the turbulent kinetic energy excess and deficit observed in the wake velocity spectra.

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Measurement of atmospheric boundary layer based on super-large-scale particle image velocimetry using natural snowfall

Cited by 46 publications

References 42 publications

A Comparative Analysis on the Response of a Wind-Turbine Model to Atmospheric and Terrain Effects

A Comparative Analysis on the Response of a Wind-Turbine Model to Atmospheric and Terrain Effects

Natural snowfall reveals large-scale flow structures in the wake of a 2.5-MW wind turbine

The spectral signature of wind turbine wake meandering: A wind tunnel and field‐scale study

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