Influences of atmospheric boundary layer turbulence structure on the space-time variability in wind turbine blade and shaft loadings

Ganesh Vijayakumar, Adam W. Lavely, Michael P. Kinzel, Eric G. Paterson, James G. Brasseur

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The atmospheric boundary layer (ABL) contains turbulence structure that is tied to its global stability state. The spatio-temporal structure of the wind vectors that pass through a large wind turbine rotor disk force loadings with variations associated with the turbulence structure of the ABL, and therefore related to global stability. We present here an analysis of daytime ABL structure in relationship to wind turbine loading by coupling well resolved spectral large-eddy simulation of canonical neutral boundary layer (NBL) and moderately convective boundary layers (MCBL) to the NREL FAST/Aerodyn design-level tool based on the Blade Element Method using the NREL 5 MW turbine with 126 m rotor disk. The loadings underlying power are significantly enhanced by the presence of atmospheric turbulence (relative to mean velocity alone). The horizontal scale of the ABL energy-dominant eddies is of order the rotor diameter. As these eddies sweep through the rotor disk, the distribution of fluctuations in rotor loadings change according to the structure of the thermal eddies with upward vs. downward motions, and horizontal eddies with high-speed vs. low-speed motions (relative to the mean). In the MCBL the up/down eddy structures are correlated with the high/low speed motions, and there is are significant differences in the high/low-speed structures between the NBL and MCBL that impact blade loadings. To better understand the structure and stability-based differences we designed a method to condition the velocity field based on strong up/downward and high/low speed motions on filtered planes of velocity data at hub height. Based on this condition, the variations in conditional mean winds between up/down and high/low large eddy structures are ∼ 4 m/s and the wind turbine experiences these variations over time scales ∼ 1-3 minutes, or 10 35 rotor revolutions, sufficiently long to include in control strategies.

Original languageEnglish (US)
Title of host publication6th AIAA Theoretical Fluid Mechanics Conference
StatePublished - Dec 1 2011
Event6th AIAA Theoretical Fluid Mechanics Conference - Honolulu, HI, United States
Duration: Jun 27 2011Jun 30 2011

Publication series

Name6th AIAA Theoretical Fluid Mechanics Conference

Other

Other6th AIAA Theoretical Fluid Mechanics Conference
CountryUnited States
CityHonolulu, HI
Period6/27/116/30/11

Fingerprint

Atmospheric boundary layer
Wind turbines
Turbomachine blades
Turbulence
Rotors
Boundary layers
Atmospheric turbulence
Large eddy simulation
Turbines

All Science Journal Classification (ASJC) codes

  • Fluid Flow and Transfer Processes

Cite this

Vijayakumar, G., Lavely, A. W., Kinzel, M. P., Paterson, E. G., & Brasseur, J. G. (2011). Influences of atmospheric boundary layer turbulence structure on the space-time variability in wind turbine blade and shaft loadings. In 6th AIAA Theoretical Fluid Mechanics Conference (6th AIAA Theoretical Fluid Mechanics Conference).
Vijayakumar, Ganesh ; Lavely, Adam W. ; Kinzel, Michael P. ; Paterson, Eric G. ; Brasseur, James G. / Influences of atmospheric boundary layer turbulence structure on the space-time variability in wind turbine blade and shaft loadings. 6th AIAA Theoretical Fluid Mechanics Conference. 2011. (6th AIAA Theoretical Fluid Mechanics Conference).
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Vijayakumar, G, Lavely, AW, Kinzel, MP, Paterson, EG & Brasseur, JG 2011, Influences of atmospheric boundary layer turbulence structure on the space-time variability in wind turbine blade and shaft loadings. in 6th AIAA Theoretical Fluid Mechanics Conference. 6th AIAA Theoretical Fluid Mechanics Conference, 6th AIAA Theoretical Fluid Mechanics Conference, Honolulu, HI, United States, 6/27/11.

Influences of atmospheric boundary layer turbulence structure on the space-time variability in wind turbine blade and shaft loadings. / Vijayakumar, Ganesh; Lavely, Adam W.; Kinzel, Michael P.; Paterson, Eric G.; Brasseur, James G.

6th AIAA Theoretical Fluid Mechanics Conference. 2011. (6th AIAA Theoretical Fluid Mechanics Conference).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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N2 - The atmospheric boundary layer (ABL) contains turbulence structure that is tied to its global stability state. The spatio-temporal structure of the wind vectors that pass through a large wind turbine rotor disk force loadings with variations associated with the turbulence structure of the ABL, and therefore related to global stability. We present here an analysis of daytime ABL structure in relationship to wind turbine loading by coupling well resolved spectral large-eddy simulation of canonical neutral boundary layer (NBL) and moderately convective boundary layers (MCBL) to the NREL FAST/Aerodyn design-level tool based on the Blade Element Method using the NREL 5 MW turbine with 126 m rotor disk. The loadings underlying power are significantly enhanced by the presence of atmospheric turbulence (relative to mean velocity alone). The horizontal scale of the ABL energy-dominant eddies is of order the rotor diameter. As these eddies sweep through the rotor disk, the distribution of fluctuations in rotor loadings change according to the structure of the thermal eddies with upward vs. downward motions, and horizontal eddies with high-speed vs. low-speed motions (relative to the mean). In the MCBL the up/down eddy structures are correlated with the high/low speed motions, and there is are significant differences in the high/low-speed structures between the NBL and MCBL that impact blade loadings. To better understand the structure and stability-based differences we designed a method to condition the velocity field based on strong up/downward and high/low speed motions on filtered planes of velocity data at hub height. Based on this condition, the variations in conditional mean winds between up/down and high/low large eddy structures are ∼ 4 m/s and the wind turbine experiences these variations over time scales ∼ 1-3 minutes, or 10 35 rotor revolutions, sufficiently long to include in control strategies.

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Vijayakumar G, Lavely AW, Kinzel MP, Paterson EG, Brasseur JG. Influences of atmospheric boundary layer turbulence structure on the space-time variability in wind turbine blade and shaft loadings. In 6th AIAA Theoretical Fluid Mechanics Conference. 2011. (6th AIAA Theoretical Fluid Mechanics Conference).