RANS Computations of Wind Turbine Near-Wake Aerodynamics in Uniform and Yawed Inflow

2013 ◽  
Author(s):  
C. Tsalicoglou ◽  
S. Jafari ◽  
N. Chokani ◽  
R. S. Abhari
Keyword(s):  
Wind Turbine ◽  
Wind Farms ◽  
Computational Effort ◽  
Speed Ratio ◽  
Flow Properties ◽  
Horizontal Axis Wind Turbine ◽  
Near Wake ◽  
Measured Flow ◽  
Rans Simulations ◽  
Good Agreement

Full RANS simulations of the flow in the near wake of a three-bladed horizontal-axis wind turbine are presented. The simulations, which are based on the MEXICO experiment and include the complete rotor, nacelle and tower, show good agreement with experimental data, with 4% difference relative to measured flow properties. The flow properties in the near wake are detailed for both uniform and non-uniform flow conditions. The effects of increasing tip-speed ratio and of yawed inflow of 30° are studied. The full RANS simulations are used to support the development of an immersed wind turbine model at ETH Zurich. This model allows for modeling of the wake evolution and interactions in wind farms, for multiple turbines, with substantially reduced computational effort.

RANS Computations of MEXICO Rotor in Uniform and Yawed Inflow

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Christina Tsalicoglou ◽  
Samira Jafari ◽  
Ndaona Chokani ◽  
Reza S. Abhari
Keyword(s):  
Wind Turbine ◽  
Wind Farms ◽  
Computational Effort ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Flow Properties ◽  
Horizontal Axis Wind Turbine ◽  
Near Wake ◽  
Measured Flow ◽  
Rans Simulations

Full Reynolds-averaged Navier–Stokes (RANS) simulations of the flow in the near wake of a three-bladed horizontal-axis wind turbine are presented. The simulations, which are based on the model experiments in controlled conditions (MEXICO) experiment and include the complete rotor, nacelle, and tower show good agreement with experimental data, with 4% difference relative to measured flow properties. The flow properties in the near wake are detailed for both uniform and nonuniform flow conditions. The effects of increasing tip-speed ratio and a yawed inflow of 30 deg are studied. The full RANS simulations are used to support the development of an immersed wind turbine model at ETH Zurich. This model allows for modeling of the wake evolution and interactions in wind farms, for multiple turbines, with substantially reduced computational effort.

scholarly journals Effect of Wind Tunnel Blockage on the Performance of a Horizontal Axis Wind Turbine with Different Blade Number

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1988 ◽  
Author(s):  
Abdelgalil Eltayesh ◽  
Magdy Bassily Hanna ◽  
Francesco Castellani ◽  
A.S. Huzayyin ◽  
Hesham M. El-Batsh ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Computational Effort ◽  
Horizontal Axis ◽  
Experimental Results ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Small Scale ◽  
Horizontal Axis Wind Turbine ◽  
Cross Section Area

Blockage corrections for the experimental results obtained for a small-scale wind turbine in a wind tunnel are required in order to estimate how the same turbine would perform in real conditions. The tunnel blockage is defined as the ratio of the wind turbine swept area to the wind tunnel cross-section area. Experimental measurements of the power coefficient were performed on a horizontal-axis wind turbine with two rotors of diameter equal to 2 m and different numbers of blades, namely three and five. Measurements were carried out for different tip speed ratios in the closed circuit open test section wind tunnel of the University of Perugia (Italy). The obtained experimental results were compared with the numerical ones carried out in free conditions by using a CFD approach based on the steady-RANS method with the SST k-ω turbulence model, adopting the multiple reference frame (MRF) strategy to reduce the computational effort. The comparison showed that the maximum value of blockage, which is reached in the asymptotic limit at very large tip speed ratio (TSR) values, does not depend appreciably on the number of blades. A higher number of blades, however, makes the occurrence of the maximum blockage come earlier at lower TSRs.

scholarly journals Modeling and simulation of forces applied to the horizontal axis wind turbine rotors by the vortex method coupled with the method of the blade element

2021 ◽  
Vol 12 (1) ◽  
pp. 413
Author(s):  
Ibtissem Barkat ◽  
Abdelouahab Benretem ◽  
Fawaz Massouh ◽  
Issam Meghlaoui ◽  
Ahlem Chebel
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farms ◽  
Vortex Method ◽  
Operating Conditions ◽  
Horizontal Axis ◽  
Rotor Blades ◽  
Good Representation ◽  
Horizontal Axis Wind Turbine ◽  
Blade Element

This article aims to study the forces applied to the rotors of horizontal axis wind turbines. The aerodynamics of a turbine are controlled by the flow around the rotor, or estimate of air charges on the rotor blades under various operating conditions and their relation to the structural dynamics of the rotor are critical for design. One of the major challenges in wind turbine aerodynamics is to predict the forces on the blade as various methods, including blade element moment theory (BEM), the approach that is naturally adapted to the simulation of the aerodynamics of wind turbines and the dynamic and models (CFD) that describes with fidelity the flow around the rotor. In our article we proposed a modeling method and a simulation of the forces applied to the horizontal axis wind rotors turbines using the application of the blade elements method to model the rotor and the vortex method of free wake modeling in order to develop a rotor model, which can be used to study wind farms. This model is intended to speed up the calculation, guaranteeing a good representation of the aerodynamic loads exerted by the wind.

A Simplified Free Wake Method for Horizontal-Axis Wind Turbine Performance Prediction

1986 ◽  
Vol 108 (4) ◽  
pp. 400-406 ◽  
Author(s):  
A. A. Afjeh ◽  
T. G. Keith
Keyword(s):  
Wind Turbine ◽  
Performance Prediction ◽  
Vortex Method ◽  
Computational Effort ◽  
Horizontal Axis ◽  
Tip Vortex ◽  
Performance Parameters ◽  
Horizontal Axis Wind Turbine ◽  
Turbine Performance ◽  
Free Wake

Based on the assumption that wake geometry of a horizontal-axis wind turbine closely resembles that of a hovering helicopter, a method is presented for predicting the performance of a horizontal-axis wind turbine. A vortex method is used in which the wake is composed of an intense tip-vortex and a diffused inboard wake. Performance parameters are calculated by application of the Biot-Savart law along with the Kutta-Joukowski theorem. Predictions are shown to compare favorably with values from a more complicated full free wake analysis and with existing experimental data, but require more computational effort than an existing fast free wake method.

Flow characterization in the near-wake region of a horizontal axis wind turbine

Wind Energy ◽  
2015 ◽  
Vol 19 (7) ◽  
pp. 1249-1267 ◽  
Author(s):  
Pooyan Hashemi Tari ◽  
Kamran Siddiqui ◽  
Horia Hangan
Keyword(s):  
Wind Turbine ◽  
Horizontal Axis ◽  
Wake Region ◽  
Horizontal Axis Wind Turbine ◽  
Near Wake ◽  
Flow Characterization

scholarly journals Investigation into Yaw Motion Influence of Horizontal-Axis Wind Turbine on Wake Flow Using LBM-LES

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5248
Author(s):  
Weimin Wu ◽  
Xiongfei Liu ◽  
Jingcheng Liu ◽  
Shunpeng Zeng ◽  
Chuande Zhou ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Aerodynamic Characteristics ◽  
Angular Speed ◽  
Aerodynamic Performance ◽  
Tip Vortex ◽  
Wake Flow ◽  
Horizontal Axis Wind Turbine ◽  
Near Wake ◽  
Eddy Simulation ◽  
Sweep Surface

The dynamic yaw motion of the wind turbine will affect the overall aerodynamic performance of the impeller and the corresponding wake flow, but the current research on this issue is inadequate. Thus, it is very necessary to study the complicated near-wake aerodynamic behaviors during the yaw process and the closely related blade aerodynamic characteristics. This work utilized the multi-relaxation time lattice Boltzmann (MRT-LBM) model to investigate the integral aerodynamic performance characteristics of the specified impeller and the dynamic changes in the near wake under a sine yawing process, in which the normalized result is adopted to facilitate data comparison and understanding. Moreover, considering the complexity of the wake flows, the large eddy simulation (LES) and wall-adapting local eddy-viscosity (WALE) model are also used in this investigation. The related results indicate that the degree of stability of tip spiral wake in the dynamic yaw condition is inversely related to the absolute value of the change rate of yaw angular speed. When the wind turbine returns to the position with the yaw angle of 0 (deg) around, the linearized migration of tip vortex is changed, and the speed loss in the wake center is reduced at about the normalized velocity of 0.27, and another transverse expansion appeared. The directional inducing downstream of the impeller sweep surface for tip vortex is clearly reflected on the entering side and the exiting side. Additionally, the features of the static pressure on the blade surface and the overall aerodynamic effects of the impeller are also discussed, respectively.

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