Fixed Bottom Wind Turbine Wave-Wake Interaction

2021 ◽  
Author(s):  
◽  
Ondrej Fercak
Keyword(s):  
Wind Turbine ◽  
Wake Interaction

Individual Pitch Control for Wind Turbine Load Reduction Enhanced With Inter-Turbine Wake Modelling

2011 ◽  
Author(s):  
Zhongzhou Yang ◽  
Yaoyu Li ◽  
John E. Seem
Keyword(s):  
Wind Turbine ◽  
State Space ◽  
Wind Profile ◽  
State Space Models ◽  
Load Reduction ◽  
Pitch Control ◽  
Wake Interaction ◽  
Wake Model ◽  
Individual Pitch Control ◽  
Turbine Wake

Individual pitch control (IPC) for wind turbine load reduction in Region 3 operation is improved when wake interaction is considered. The Larsen wake model is applied for composing the rotor wind profile for downstream turbines under wake interaction. The wind profile of the turbine wake was generated by modifying the NREL’s TurbSim codes. The state-space models of wind turbine were obtained via linearization of wind turbine model available in the NREL’s aeroelastic design code FAST. In particular, in order to obtain more accurate state-space models, equivalent circular wind profile was generated so as to better determine the local pitch reference. Based on such models, IPC controllers were designed following the disturbance accommodating control (DAC) and periodic control framework. The simulation results showed that the turbine loads can be further reduced using the switching control scheme based on wake modeling, as compared with the generic DAC without wake consideration.

Effects From Complex Terrain on Wind-Turbine Performance

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Ann Hyvärinen ◽  
Antonio Segalini
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Wind Turbine ◽  
Complex Terrain ◽  
Positive Impact ◽  
Interaction Effects ◽  
Turbine Performance ◽  
Turbulent Inflow ◽  
Wake Interaction ◽  
Inflow Conditions

In this work, experimental measurements are made to study wind turbines over complex terrains and in presence of the atmospheric boundary layer. Thrust and power coefficients for single and multiple turbines are measured when introducing sinusoidal hills and spires inducing an artificial atmospheric boundary layer. Additionally, wake interaction effects are studied, and inflow velocity profiles are characterized using hot-wire anemometry. The results indicate that the introduced hills have a positive impact on the wind-turbine performance and that wake-interaction effects are significantly reduced during turbulent inflow conditions.

scholarly journals Simulation of wind turbine wake interaction using the vorticity transport model

Wind Energy ◽  
2009 ◽  
Vol 13 (7) ◽  
pp. 587-602 ◽  
Author(s):  
Timothy M. Fletcher ◽  
Richard E. Brown
Keyword(s):  
Wind Turbine ◽  
Transport Model ◽  
Wake Interaction ◽  
Vorticity Transport ◽  
Turbine Wake ◽  
Wind Turbine Wake

scholarly journals Optimized Placement of Onshore Wind Farms Considering Topography

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2944 ◽  
Author(s):  
Xiawei Wu ◽  
Weihao Hu ◽  
Qi Huang ◽  
Cong Chen ◽  
Zhe Chen ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Production Cost ◽  
Wind Farms ◽  
Power Production ◽  
Optimization Method ◽  
Wake Effect ◽  
Onshore Wind ◽  
Wake Interaction ◽  
Height Change

As the scale of onshore wind farms are increasing, the influence of wake behavior on power production becomes increasingly significant. Wind turbines sittings in onshore wind farms should take terrain into consideration including height change and slope curvature. However, optimized wind turbine (WT) placement for onshore wind farms considering both topographic amplitude and wake interaction is realistic. In this paper, an approach for optimized placement of onshore wind farms considering the topography as well as the wake effect is proposed. Based on minimizing the levelized production cost (LPC), the placement of WTs was optimized considering topography and the effect of this on WTs interactions. The results indicated that the proposed method was effective for finding the optimized layout for uneven onshore wind farms. The optimization method is applicable for optimized placement of onshore wind farms and can be extended to different topographic conditions.

Wake to wake interaction of floating wind turbine models in free pitch motion: An eddy viscosity and mixing length approach

2016 ◽  
Vol 85 ◽  
pp. 666-676 ◽  
Author(s):  
Stanislav Rockel ◽  
Joachim Peinke ◽  
Michael Hölling ◽  
Raúl Bayoán Cal
Keyword(s):  
Wind Turbine ◽  
Eddy Viscosity ◽  
Mixing Length ◽  
Pitch Motion ◽  
Floating Wind Turbine ◽  
Wake Interaction

Blade-Wake Interaction Noise for Turbines With Downwind Rotors

2003 ◽  
Vol 125 (4) ◽  
pp. 497-505 ◽  
Author(s):  
G. M. McNerney ◽  
C. P. van Dam ◽  
D. T. Yen-Nakafuji
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Incidence Angle ◽  
Dynamic Pressure ◽  
Low Frequency ◽  
Frequency Noise ◽  
Atmospheric Conditions ◽  
Noise Mitigation ◽  
Local Flow ◽  
Wake Interaction

The interaction between the rotor and the tower wake is an important source of noise for wind turbines with downwind rotors. The tower wake modifies the dynamic pressure and the local flow incidence angle as seen by the blades and, hence, modifies the aerodynamic loading of the blade during blade passage. The resulting n per revolution fluctuation in the blade loading (where n is the number of blades) is the source of low frequency but potentially high amplitude sound levels. The Wind Turbine Company (WTC) Proof of Concept 250 kW (POC) wind turbine has been observed by field personnel to produce low-frequency emissions at the National Wind Technology Center (NWTC) site during specific atmospheric conditions. Consequently, WTC is conducting a three-phase program to characterize the low frequency emissions of its two-bladed wind turbines and to develop noise mitigation techniques if needed. This paper summarizes the first phase of this program including recent low-frequency noise measurements conducted on the WTC POC250 kW wind turbine, a review of the wake characteristics of circular towers as they pertain to the blade-wake interaction problem, and techniques to attenuate the sound pressure levels caused by the blade-wake interaction.

scholarly journals Validation of the actuator disc approach using small-scale model wind turbines

2017 ◽  
Vol 2 (2) ◽  
pp. 587-601 ◽  
Author(s):  
Nikolaos Simisiroglou ◽  
Simon-Philippe Breton ◽  
Stefan Ivanell
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbulence Intensity ◽  
Computational Effort ◽  
Scale Model ◽  
Small Scale ◽  
Thrust Coefficient ◽  
Line Model ◽  
Wake Interaction ◽  
Actuator Disc

Abstract. The aim of the present study is the validation of the implementation of an actuator disc (ACD) model in the computational fluid dynamics (CFD) code PHOENICS. The flow behaviour for three wind turbine cases is investigated numerically and compared to wind tunnel measurements: (A) the flow around a single model wind turbine, (B) the wake interaction between two in-line model wind turbines for a uniform inflow of low turbulence intensity and (C) the wake interaction between two in-line model wind turbines at different separation distances in a uniform or sheared inflow of high turbulence intensity. This is carried out using Reynolds-averaged Navier–Stokes (RANS) simulations and an ACD technique in the CFD code PHOENICS. The computations are conducted for the design condition of the rotors using four different turbulence closure models and five different thrust distributions. The computed axial velocity field as well as the turbulence kinetic energy are compared with hot-wire anemometry (HWA) measurements. For the cases with two in-line wind turbines, the thrust coefficient is also computed and compared with measurements. The results show that for different inflow conditions and wind turbine spacings the proposed method is able to predict the overall behaviour of the flow with low computational effort. When using the k-ε and Kato–Launder k-ε turbulence models the results are generally in closer agreement with the measurements.

Blade-Wake Interaction Noise for Turbines With Downwind Rotors

2003 ◽  
Author(s):  
G. M. McNerney ◽  
C. P. van Dam ◽  
D. T. Yen-Nakafuji
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Dynamic Pressure ◽  
Circular Cross Section ◽  
Low Frequency ◽  
Frequency Noise ◽  
Noise Mitigation ◽  
Local Flow ◽  
Wake Interaction ◽  
Wake Characteristics

The interaction between the rotor and the tower wake is an important source of noise for wind turbines with downwind rotors. These noise levels may significantly impact the immediate environment. During rotation the rotor blades encounter periodic changes in flow conditions as a result of the tower presence. Typically turbine towers have a circular or modified circular cross section which significantly modifies the flow in the vicinity of the tower. Upstream, the tower causes the flow to decelerate and, hence, causes a rise in pressure. Because of its bluff shape, the flow separates prematurely from the tower and this tends to create a wide, unsteady, vortical wake. The wake characteristics are dependent on the cross-sectional shape of the tower, its surface properties, the Reynolds number (based on tower diameter and wind velocity) of the flow, and the turbulence level of the incoming flow. The wake modifies the dynamic pressure and the local flow incidence angle as seen by the blades and, hence, modifies the aerodynamic loading of the blade during blade passage. The resulting n per revolution fluctuation in the blade loading (where n is the number of blades) is the source of low frequency but potentially high amplitude sound levels. The WTC Proof of Concept 250 kW (POC) wind turbine has been observed by field personnel to produce low frequency emissions at the National Wind Technology Center (NWTC) site during specific atmospheric conditions. Consequently, WTC is conducting a three-phase program to characterize the low frequency emissions of its two-bladed wind turbines and to develop noise mitigation techniques if needed. This paper summarizes the first phase of this program including recent low-frequency noise measurements conducted on the WTC POC250 kW wind turbine, the wake characteristics of circular towers as they pertain to the blade-wake interaction problem, and techniques to attenuate the sound pressure levels caused by the blade-wake interaction.

scholarly journals Simulation of wind turbine wakes using the actuator line technique

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140071 ◽  
Author(s):  
Jens N. Sørensen ◽  
Robert F. Mikkelsen ◽  
Dan S. Henningson ◽  
Stefan Ivanell ◽  
Sasan Sarmast ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Analytical Formula ◽  
Decomposition Analysis ◽  
Wind Farms ◽  
Near Wake ◽  
Performance Predictions ◽  
Wake Interaction ◽  
Large Eddy ◽  
Basic Features ◽  
Proper Orthogonal

The actuator line technique was introduced as a numerical tool to be employed in combination with large eddy simulations to enable the study of wakes and wake interaction in wind farms. The technique is today largely used for studying basic features of wakes as well as for making performance predictions of wind farms. In this paper, we give a short introduction to the wake problem and the actuator line methodology and present a study in which the technique is employed to determine the near-wake properties of wind turbines. The presented results include a comparison of experimental results of the wake characteristics of the flow around a three-bladed model wind turbine, the development of a simple analytical formula for determining the near-wake length behind a wind turbine and a detailed investigation of wake structures based on proper orthogonal decomposition analysis of numerically generated snapshots of the wake.

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