scholarly journals A New Method of Determination of the Angle of Attack on Rotating Wind Turbine Blades

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 4012
Author(s):  
Wei Zhong ◽  
Wen Zhong Shen ◽  
Tong Guang Wang ◽  
Wei Jun Zhu
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Flow Characteristics ◽  
New Method ◽  
Wind Turbine Blades ◽  
Monitoring Point ◽  
Local Flow ◽  
Determination Methods

The angle of attack (AoA) is the key parameter when extracting the aerodynamic polar from the rotating blade sections of a wind turbine. However, the determination of AoA is not straightforward using computational fluid dynamics (CFD) or measurement. Since the incoming streamlines are bent because of the complex inductions of the rotor, discrepancies exist between various existing determination methods, especially in the tip region. In the present study, flow characteristics in the region near wind turbine blades are analyzed in detail using CFD results of flows past the NREL UAE Phase VI rotor. It is found that the local flow determining AOA changes rapidly in the vicinity of the blade. Based on this finding, the concepts of effective AoA as well as nominal AoA are introduced, leading to a new method of AOA determination. The new method has 5 steps: (1) Find the distributed vortices on the blade surface; (2) select two monitoring points per cross-section close to the aerodynamic center on both pressure and suction sides with an equal distance from the rotor plane; (3) subtract the blade self-induction from the velocity at each monitoring point; (4) average the velocity of the two monitoring points obtained in Step 3; (5) determine the AoA using the velocity obtained in Step 4. Since the monitoring points for the first time can be set very close to the aerodynamic center, leading to an excellent estimation of AoA. The aerodynamic polar extracted through determination of the effective AoA exhibits a consistent regularity for both the mid-board and tip sections, which has never been obtained by the existing determination methods.

Evaluation of the influence of wind speed and angle of attack on the aerodynamic effect of wind turbine blades

2017 ◽  
Author(s):  
Salete Alves ◽  
Luiz Guilherme Vieira Meira de Souza ◽  
Edália Azevedo de Faria ◽  
Maria Thereza dos Santos Silva ◽  
Ranaildo Silva
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Wind Turbine Blades ◽  
Aerodynamic Effect

Uncertainty prediction on the angle of attack of wind turbine blades based on the field measurements

Energy ◽  
2020 ◽  
Vol 200 ◽  
pp. 117515
Author(s):  
Guangxing Wu ◽  
Chaoyu Zhang ◽  
Chang Cai ◽  
Ke Yang ◽  
Kezhong Shi
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Field Measurements ◽  
Wind Turbine Blades ◽  
Uncertainty Prediction

Design and Evaluation of a Rooftop Wind Turbine Rotor With Untwisted Blades

2013 ◽  
Author(s):  
Sayem Zafar ◽  
Mohamed Gadalla
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Low Cost ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Turbine Rotor ◽  
Wind Turbine Blades ◽  
Wind Speeds ◽  
Small Wind Turbines ◽  
Wind Turbine Rotor

A small horizontal axis wind turbine rotor was designed and tested with aerodynamically efficient, economical and easy to manufacture blades. Basic blade aerodynamic analysis was conducted using commercially available software. The blade span was constrained such that the complete wind turbine can be rooftop mountable with the envisioned wind turbine height of around 8 m. The blade was designed without any taper or twist to comply with the low cost and ease of manufacturing requirements. The aerodynamic analysis suggested laminar flow airfoils to be the most efficient airfoils for such use. Using NACA 63-418 airfoil, a rectangular blade geometry was selected with chord length of 0.27[m] and span of 1.52[m]. Glass reinforced plastic was used as the blade material for low cost and favorable strength to weight ratio with a skin thickness of 1[mm]. Because of the resultant velocity changes with respect to the blade span, while the blade is rotating, an optimal installed angle of attack was to be determined. The installed angle of attack was required to produce the highest possible rotation under usual wind speeds while start at relatively low speed. Tests were conducted at multiple wind speeds with blades mounted on free rotating shaft. The turbine was tested for three different installed angles and rotational speeds were recorded. The result showed increase in rotational speed with the increase in blade angle away from the free-stream velocity direction while the start-up speeds were found to be within close range of each other. At the optimal angle was found to be 22° from the plane of rotation. The results seem very promising for a low cost small wind turbine with no twist and taper in the blade. The tests established that non-twisted wind turbine blades, when used for rooftop small wind turbines, can generate useable electrical power for domestic consumption. It also established that, for small wind turbines, non-twisted, non-tapered blades provide an economical yet productive alternative to the existing complex wind turbine blades.

Numerical Shape Optimization of a Wind Turbine Blades Using Artificial Bee Colony Algorithm

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Shahram Derakhshan ◽  
Ali Tavaziani ◽  
Nemat Kasaeian
Keyword(s):  
Flow Field ◽  
Shape Optimization ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Artificial Bee Colony ◽  
Twist Angle ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Wind Turbine Blades ◽  
Bee Colony

Use of wind turbines is rapidly growing because of environmental impacts and daily increase in energy cost. Therefore, improving the wind turbines' characteristics is an important issue in this regard. This study has two objectives: one is investigating the aerodynamic performance of wind turbine blades and the other is developing an efficient approach for shape optimization of blades. The numerical solver of flow field was validated by phase VI rotor as a case study. First, flow field around the wind turbine blades was simulated using computational flow dynamics (CFD) and blade element momentum (BEM) methods, then obtained results were validated by available experimental data to show an appropriate conformity. Then for yielding the optimal answer, a shape optimization algorithm was used based on artificial bee colony (ABC) coupled by artificial neural networks (ANNs) as an approximate model. Effect of most important parameters in wind turbine, such as twist angle, chord line, and pitch angle, was changed till achieving the best performance. The flow characteristics of optimized and initial geometries were compared. The results of global optimization showed a value of 8.58% increase for output power. By using pitch power regulate, the maximum power was shifted to higher wind speed and results in a steady power for all work points.

scholarly journals Determination of the number of Vertical Axis Wind Turbine blades based on power spectrum

2017 ◽  
Vol 19 ◽  
pp. 01003 ◽  
Author(s):  
Waldemar Fedak ◽  
Stanisław Anweiler ◽  
Wojciech Gancarski ◽  
Roman Ulbrich
Keyword(s):  
Power Spectrum ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Wind Turbine Blades

Dynamic Stall on Rotating Airfoils: A Look at the N-Sequence Data from the NREL Phase VI Experiment

2013 ◽  
Vol 569-570 ◽  
pp. 611-619 ◽  
Author(s):  
Srinivas Guntur ◽  
Niels N. Sørensen ◽  
Scott Schreck
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
Sequence Data ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Dynamic Stall ◽  
Wind Turbine Blades ◽  
Flow Solver ◽  
The Mean ◽  
Nrel Phase Vi

This paper presents an investigation on the combined effect of dynamic stall and rotational augmentation on wind turbine blades. Dynamic stall and rotational augmentation have previously been studied independently. The NREL Phase VI experiment was one large scale experiment that recorded 3D measurements on rotating and pitching airfoils, and using some these data the behaviour of the unsteady CL-α polars under the influence of rotation is investigated. Unsteady DES CFD computations of the Phase VI rotor in axial operation and continuous pitching conditions (reproducing conditions similar to the N-sequence experiments) for select cases have also been carried out using the in-house flow solver EllipSys3D. The resulting set of CL-α curves for the airfoils in rotation operating at various values of the frequency, the mean, and the amplitude of the angle of attack resulting from the CFD computations as well as those from the experiments are presented and discussed. Qualitative differences between dynamic stall occurrence on rotating and stationary airfoils are highlighted, procedures employed to extract the mean angle of attack from the available experimental data are discussed, and comments are made on the application of dynamic stall models in conjunction with 3D augmentation models on the rotating wind turbine blades.

scholarly journals Brief communication: Extraction of the wake induction and angle of attack on rotating wind turbine blades from PIV and CFD results

2017 ◽  
Author(s):  
Iván Herráez ◽  
Elia Daniele ◽  
J. Gerard Schepers
Keyword(s):  
New Mexico ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Accurate Information ◽  
Wind Turbine Blades ◽  
Cfd Simulations ◽  
Wind Turbine Aerodynamics ◽  
First Time ◽  
Local Angle

Abstract. The analysis of wind turbine aerodynamics requires accurate information about the axial and tangential wake induction as well as the local angle of attack along the blades. In this work, we present a new method for obtaining them conveniently from the velocity field. We apply the method to the New Mexico PIV-dataset and to CFD simulations of the same turbine. This allows comparing for the first time experimental and numerical results of the mentioned quantities on a rotating wind turbine. The presented results open up new possibilities for the validation of numerical rotor models.

Sign in / Sign up

Export Citation Format

Share Document