Wind Shear and Turbulence Effects on Rotor Fatigue and Loads Control

Eggers, A. J.; Digumarthi, R.; Chaney, K.

doi:10.1115/1.1629752

Cited by 38 publications

(34 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To answer this question, we use published results based on standardized simulation methods. Eggers et al . used the YawDyn/Aerodyn code to analyze loads from wind shear on a turbine with an 84 m hub height and a 35 m rotor radius ( R * = 0.417).…”

Section: Resultsmentioning

confidence: 99%

“…Although the dimensionless moment is only a function of R * and m , the actual moment depends on the design attributes specific to the turbine. According to Eggers et al ., this system produces P = 1.5 MW at 12 m s −1 . Using these data with momentum theory,

P = 2 ρ A V_{h}^{3} \cdot a \cdot {(1 - a)}^{2}

, gives an effective axial induction factor of a = 0.118 (for this system at this speed); the corresponding nominal thrust is

F_{0} = 2 ρ \cdot A \cdot V_{h}^{2} \cdot a \cdot ((), 1 - a) = 141 normalk normalN

.…”

Section: Resultsmentioning

confidence: 99%

“…From momentum theory, the thrust on a differential ring of a general rotor at radius, r , is dF Z = 4 πρ ⋅ r ⋅ V ( y ) 2 ⋅ ( a − a 2 ) ⋅ dr . The differential thrust is only a function of air density, radius, wind speed and the axial induction factor, a , which is governed by blade aerodynamics.…”

Section: Wind Shear Modelmentioning

confidence: 99%

See 2 more Smart Citations

Effects of wind shear on wind turbine rotor loads and planetary bearing reliability

Gould

Burris

2015

Wind Energy

View full text Add to dashboard Cite

Recent studies suggest that wind shear and the resulting pitch moments increase bearing loads and thereby contribute to premature wind turbine gearbox failure. In this paper, we use momentum‐based modeling approaches to predict the pitch moments from wind shear. The non‐dimensionalized results, which have been validated against accepted aeroelastic results, can be used to determine thrust force, pitch moment and power of a general rotor as a function of the wind shear exponent. Even in extreme wind shear (m = 1), the actual thrust force and power for a typical turbine (R* < 0.5) were within 8% and 20% of the nominal values (those without wind shear), respectively. The mean pitch moment increased monotonically with turbine thrust, rotor radius and wind shear exponent. For extreme wind shear (m = 1) on a typical turbine (R* = 0.5), the mean pitch moment is ~25% the product of thrust force and rotor radius. Analysis of wind shear for a typical 750 kW turbine revealed that wind shear does not significantly affect bearing loads because it counteracts the effects of rotor weight. Furthermore, even though general pitch moments did significantly increase bearing loads, they were found to be unlikely to cause bearing fatigue. Analyses of more common low wind‐speed cases suggest that bearing under‐loading and wear are more likely to contribute to premature bearing failure than overloading and classical surface contact fatigue. Copyright © 2015 John Wiley & Sons, Ltd.

show abstract

Section: Resultsmentioning

confidence: 99%

P = 2 ρ A V_{h}^{3} \cdot a \cdot {(1 - a)}^{2}

, gives an effective axial induction factor of a = 0.118 (for this system at this speed); the corresponding nominal thrust is

F_{0} = 2 ρ \cdot A \cdot V_{h}^{2} \cdot a \cdot ((), 1 - a) = 141 normalk normalN

.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Effects of wind shear on wind turbine rotor loads and planetary bearing reliability

Gould

Burris

2015

Wind Energy

View full text Add to dashboard Cite

show abstract

“…While LLJs often greatly increase the speed of the wind in the rotor layer of a turbine (40-120 m above the ground in this study), shear and veer place additional stresses on the structure that can increase the need for regular maintenance and the possibility of mechanical failure (Eggers et al 2003;Kelley 2011). Correlation of wind speeds over large distances can also cause problems for balancing supply and demand on the energy grid if large amounts of wind-generated electricity dominate the system.…”

Section: Introductionmentioning

confidence: 89%

Observing and Simulating the Summertime Low-Level Jet in Central Iowa

Vanderwende

Lundquist

Rhodes

et al. 2015

Monthly Weather Review

View full text Add to dashboard Cite

In the U.S. state of Iowa, the increase in wind power production has motivated interest into the impacts of low-level jets on turbine performance. In this study, two commercial lidar systems were used to sample wind profiles in August 2013. Jets were systematically detected and assigned an intensity rating from 0 (weak) to 3 (strong). Many similarities were found between observed jets and the well-studied Great Plains low-level jet in summer, including average jet heights between 300 and 500 m above ground level, a preference for southerly wind directions, and a nighttime bias for stronger jets. Strong vertical wind shear and veer were observed, as well as veering over time associated with the LLJs. Speed, shear, and veer increases extended into the turbine-rotor layer during intense jets. Ramp events, in which winds rapidly increase or decrease in the rotor layer, were also commonly observed during jet formation periods. The lidar data were also used to evaluate various configurations of the Weather Research and Forecasting Model. Jet occurrence exhibited a stronger dependence on the choice of initial and boundary condition data, while reproduction of the strongest jets was influenced more strongly by the choice of planetary boundary layer scheme. A decomposition of mean model winds suggested that the main forcing mechanism for observed jets was the inertial oscillation. These results have implications for wind energy forecasting and site assessment in the Midwest.

show abstract

“…The wind shear and turbulence effects on rotor fatigue loads were studied by Eggers et al . The wind profile is modelled using the power law and turbulence using the von Kármán isotropic spectral tensor. They concluded that the increase in wind shear and turbulence increased rotor fatigue loads considerably.…”

Section: Introductionmentioning

confidence: 99%

Influence of atmospheric stability on wind turbine loads

Sathe

Mann²,

Barlas³

et al. 2012

Wind Energy

145

122

View full text Add to dashboard Cite

Simulations of wind turbine loads for the NREL 5 MW reference wind turbine under diabatic conditions are performed. The diabatic conditions are incorporated in the input wind field in the form of wind profile and turbulence. The simulations are carried out for mean wind speeds between 3 and 16 m s − 1 at the turbine hub height. The loads are quantified as the cumulative sum of the damage equivalent load for different wind speeds that are weighted according to the wind speed and stability distribution. Four sites with a different wind speed and stability distribution are used for comparison. The turbulence and wind profile from only one site is used in the load calculations, which are then weighted according to wind speed and stability distributions at different sites. It is observed that atmospheric stability influences the tower and rotor loads. The difference in the calculated tower loads using diabatic wind conditions and those obtained assuming neutral conditions only is up to 17%, whereas the difference for the rotor loads is up to 13%. The blade loads are hardly influenced by atmospheric stability, where the difference between the calculated loads using diabatic and neutral input wind conditions is up to 3% only. The wind profiles and turbulence under diabatic conditions have contrasting influences on the loads; for example, under stable conditions, loads induced by the wind profile are larger because of increased wind shear, whereas those induced by turbulence are lower because of less turbulent energy. The tower base loads are mainly influenced by diabatic turbulence, whereas the rotor loads are influenced by diabatic wind profiles. The blade loads are influenced by both, diabatic wind profile and turbulence, that leads to nullifying the contrasting influences on the loads. The importance of using a detailed boundary‐layer wind profile model is also demonstrated. The difference in the calculated blade and rotor loads is up to 6% and 8%, respectively, when only the surface‐layer wind profile model is used in comparison with those obtained using a boundary‐layer wind profile model. Finally, a comparison of the calculated loads obtained using site‐specific and International Electrotechnical Commission (IEC) wind conditions is carried out. It is observed that the IEC loads are up to 96% larger than those obtained using site‐specific wind conditions.Copyright © 2012 John Wiley & Sons, Ltd.

show abstract

Wind Shear and Turbulence Effects on Rotor Fatigue and Loads Control

Cited by 38 publications

References 2 publications

Effects of wind shear on wind turbine rotor loads and planetary bearing reliability

Effects of wind shear on wind turbine rotor loads and planetary bearing reliability

Observing and Simulating the Summertime Low-Level Jet in Central Iowa

Influence of atmospheric stability on wind turbine loads

Contact Info

Product

Resources

About