Unraveling the Mysteries of Turbulence Transport in  a Wind Farm

Jha, Pankaj; Duque, Earl P. N.; Bashioum, Jessica L.; Schmitz, Sven

doi:10.3390/en8076468

Cited by 19 publications

(9 citation statements)

References 26 publications

(52 reference statements)

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“…The wake deficit for either turbine is highest for the uniform flow case and smallest for the neutral ABL case. This behavior of the turbine wake mixing rate increasing with inflow turbulence intensity has been previously observed both experimentally [51] and numerically [52] for conventional, single-rotor turbines.…”

Section: Mean Flowsupporting

confidence: 74%

Numerical Investigation of Aerodynamic Performance and Loads of a Novel Dual Rotor Wind Turbine

2016

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Abstract:The objective of this paper is to numerically investigate the effects of the atmospheric boundary layer on the aerodynamic performance and loads of a novel dual-rotor wind turbine (DRWT). Large eddy simulations are carried out with the turbines operating in the atmospheric boundary layer (ABL) and in a uniform inflow. Two stability conditions corresponding to neutral and slightly stable atmospheres are investigated. The turbines are modeled using the actuator line method where the rotor blades are modeled as body forces. Comparisons are drawn between the DRWT and a comparable conventional single-rotor wind turbine (SRWT) to assess changes in aerodynamic efficiency and loads, as well as wake mixing and momentum and kinetic energy entrainment into the turbine wake layer. The results show that the DRWT improves isolated turbine aerodynamic performance by about 5%-6%. The DRWT also enhances turbulent axial momentum entrainment by about 3.3%. The highest entrainment is observed in the neutral stability case when the turbulence in the ABL is moderately high. Aerodynamic loads for the DRWT, measured as out-of-plane blade root bending moment, are marginally reduced. Spectral analyses of ABL cases show peaks in unsteady loads at the rotor passing frequency and its harmonics for both rotors of the DRWT.

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Section: Mean Flowsupporting

confidence: 74%

Numerical Investigation of Aerodynamic Performance and Loads of a Novel Dual Rotor Wind Turbine

2016

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“…The selected turbine is the NREL 5 MW research turbine [9], which is often used in comparative research studies [10,11]. It is a three-bladed horizontal axis upwind turbine with a rated power of 5 MW at a wind speed of 11.4 m/s and a rotational speed of 12.1 rpm.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Eroded Blades on Wind Turbine Performance Using Numerical Simulations

et al. 2017

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During their operation, wind turbine blades are eroded due to rain and hail, or they are contaminated with insects. Since the relative inflow velocity is higher at the outer than at the inner part of the blades, erosion occurs mostly at the outer blade region. In order to prevent strong erosion, it is possible to install a leading edge protection, which can be applied to the blades after the initial installation, but changes the shape of the initial airfoil sections. It is unclear how this modification influences the aerodynamic performance of the turbine. Hence, it is investigated in this work. The NREL 5 MW turbine is simulated with clean and eroded blades, which are compared to coated blades equipped with leading edge protection. Aerodynamic polars are generated by means of Computational Fluid Dynamics, and load calculations are conducted using the blade element momentum theory. The analysis in this work shows that, compared to clean rotor blades, the worse aerodynamic behaviour of strongly eroded blades can lead to power losses of 9%. In contrast, coated blades only have a small impact on the turbine power of less than 1%.

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“…Rather, our results agree with those of Wang et al (2015Wang et al ( , 2017, whose calculations are computed from the Beddoes circulation formula (Madsen and Rasmussen, 2004), as opposed to the wind tunnel extrapolation in Mulinazzi and Zheng (2014). Past successes in 20 turbine wake modeling using LES actuator-line methods can in part validate our results (e.g., Churchfield et al (2012);Nilsson et al (2015); Jha et al (2015)). …”

mentioning

confidence: 57%

“…LES have been used to investigate wind turbine wake 5 turbulence (Churchfield et al, 2012;Jha et al, 2015), the wind-farm boundary layer (Calaf et al, 2010), and the evolution of the wake structure in variable stability conditions and throughout the diurnal cycle Mirocha et al, 2014;Aitken et al, 2014b;Bhaganagar and Debnath, 2014;Mirocha et al, 2015;Abkar et al, 2016;Englberger and Dörnbrack, 2018). Jimenez et al (2007) find good agreement between LES and experimental data of turbine wakes, which has led to the use of LES to correct for instrumentation error (e.g., ).…”

Section: Simulationsmentioning

confidence: 99%

Do Wind Turbines Pose Roll Hazards to Light Aircraft?

Tomaszewski

2018

Preprint

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Abstract. Wind energy accounted for 5.6% of all electricity generation in the United States in 2016. Much of this development has occurred in rural locations, where open spaces favorable for harnessing wind also serve general aviation airports. As such, nearly 40% of all U.S. wind turbines exist within 10 km of a small airport. Wind turbines generate electricity by extracting momentum from the atmosphere, creating downwind wakes characterized by wind-speed deficits and increased turbulence.Recently, the concern that turbine wakes pose hazards for small aircraft has been used to limit wind farm development. Herein, we assess roll hazards to small aircraft using large-eddy simulations of a utility-scale turbine wake. Wind-generated rolling moments on hypothetical aircraft transecting the wake in stably and neutrally stratified conditions are calculated. In both cases, only 0.001% of rolling moments experienced by hypothetical aircraft during down-wake and cross-wake transects lead to an increased risk of rolling.

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Unraveling the Mysteries of Turbulence Transport in a Wind Farm

Cited by 19 publications

References 26 publications

Numerical Investigation of Aerodynamic Performance and Loads of a Novel Dual Rotor Wind Turbine

Numerical Investigation of Aerodynamic Performance and Loads of a Novel Dual Rotor Wind Turbine

The Influence of Eroded Blades on Wind Turbine Performance Using Numerical Simulations

Do Wind Turbines Pose Roll Hazards to Light Aircraft?

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