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

scholarly journals Analysis of Wind Turbine Aging through Operation Data Calibrated by LiDAR Measurement

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2319
Author(s):  
Hyun-Goo Kim ◽  
Jin-Young Kim
Keyword(s):  
Power Generation ◽  
Wind Speed ◽  
Wind Turbine ◽  
Wind Farm ◽  
Free Stream ◽  
Turbine Blades ◽  
Wind Farms ◽  
Lidar Measurement ◽  
Wind Turbine Blades ◽  
Wake Effect

This study analyzed the performance decline of wind turbine with age using the SCADA (Supervisory Control And Data Acquisition) data and the short-term in situ LiDAR (Light Detection and Ranging) measurements taken at the Shinan wind farm located on the coast of Bigeumdo Island in the southwestern sea of South Korea. Existing methods have generally attempted to estimate performance aging through long-term trend analysis of a normalized capacity factor in which wind speed variability is calibrated. However, this study proposes a new method using SCADA data for wind farms whose total operation period is short (less than a decade). That is, the trend of power output deficit between predicted and actual power generation was analyzed in order to estimate performance aging, wherein a theoretically predicted level of power generation was calculated by substituting a free stream wind speed projecting to a wind turbine into its power curve. To calibrate a distorted wind speed measurement in a nacelle anemometer caused by the wake effect resulting from the rotation of wind-turbine blades and the shape of the nacelle, the free stream wind speed was measured using LiDAR remote sensing as the reference data; and the nacelle transfer function, which converts nacelle wind speed into free stream wind speed, was derived. A four-year analysis of the Shinan wind farm showed that the rate of performance aging of the wind turbines was estimated to be −0.52%p/year.

scholarly journals Remaining Useful Life Estimation of Wind Turbine Blades under Variable Wind Speed Conditions Using Particle Filters

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Bhavana Valeti ◽  
Shamim N. Pakzad
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Remaining Useful Life ◽  
Structural Components ◽  
Wind Turbine Blades ◽  
Average Wind Speed ◽  
Average Wind ◽  
Useful Life ◽  
Variable Wind

Rotor blades are the most complex structural components in a wind turbine and are subjected to continuous cyclic loads of wind and self-weight variation. The structural maintenance operations in wind farms are moving towards condition based maintenance (CBM) to avoid premature failures. For this, damage prognosis with remaining useful life (RUL) estimation in wind turbine blades is necessary. Wind speed variation plays an important role influencing the loading and consequently the RUL of the structural components. This study investigates the effect of variable wind speed between the cutin and cut-out speeds of a typical wind farm on the RUL of a damage detected wind turbine blade as opposed to average wind speed assumption. RUL of wind turbine blades are estimated for different initial crack sizes using particle filtering method which forecasts the evolution of fatigue crack addressing the non-linearity and uncertainty in crack propagation. The stresses on a numerically simulated life size onshore wind turbine blade subjected to the above wind speed loading cases are used in computing the crack propagation observation data for particle filters. The effects of variable wind speed on the damage propagation rates and RUL in comparison to those at an average wind speed condition are studied and discussed.

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.

scholarly journals A Simplified Morphing Blade for Horizontal Axis Wind Turbines

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Weijun Wang ◽  
Stéphane Caro ◽  
Fouad Bennis ◽  
Oscar Roberto Salinas Mejia
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Production ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Annual Average ◽  
Average Wind Speed ◽  
Pitch Control ◽  
Average Wind

The aim of designing wind turbine blades is to improve the power capture ability. Since rotor control technology is currently limited to controlling rotational speed and blade pitch, an increasing concern has been given to morphing blades. In this paper, a simplified morphing blade is introduced, which has a linear twist distribution along the span and a shape that can be controlled by adjusting the twist of the blade's root and tip. To evaluate the performance of wind turbine blades, a numerical code based on the blade element momentum theory is developed and validated. The blade of the NREL Phase VI wind turbine is taken as a reference blade and has a fixed pitch. The optimization problems associated with the control of the morphing blade and a blade with pitch control are formulated. The optimal results show that the morphing blade gives better results than the blade with pitch control in terms of produced power. Under the assumption that at a given site, the annual average wind speed is known and the wind speed follows a Rayleigh distribution, the annual energy production of wind turbines was evaluated for three types of blade, namely, morphing blade, blade with pitch control and fixed pitch blade. For an annual average wind speed varying between 5 m/s and 15 m/s, it turns out that the annual energy production of the wind turbine containing morphing blades is 24.5% to 69.7% higher than the annual energy production of the wind turbine containing pitch fixed blades. Likewise, the annual energy production of the wind turbine containing blades with pitch control is 22.7% to 66.9% higher than the annual energy production of the wind turbine containing pitch fixed blades.

Optimal Design of Horizontal Axis Wind Turbine Blades

2008 ◽  
Author(s):  
Ohad Gur ◽  
Aviv Rosen
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Design Method ◽  
Turbine Blades ◽  
Horizontal Axis ◽  
Optimization Strategy ◽  
Wind Turbine Blades ◽  
Horizontal Axis Wind Turbine ◽  
Wind Speeds ◽  
Design Variables

The optimal aerodynamic design of Horizontal Axis Wind Turbine (HAWT) is investigated. The Blade-element/Momentum model is used for the aerodynamic analysis. In the first part of the paper a simple design method is derived, where the turbine blade is optimized for operation at a specific wind speed. Results of this simple optimization are presented and discussed. Besides being optimized for operation at a specific wind speed, without considering operation at other wind speeds, the simple model is also limited in the choice of design goals (cost functions), design variables and constraints. In the second part of the paper a comprehensive design method that is based on a mixed numerical optimization strategy, is presented. This method can handle almost any combination of: design goal, design variables, and constraints. Results of this method are presented, compared with the results of the simple optimization, and discussed.

scholarly journals Acoustic Emissions from Wind Turbine Blades

2019 ◽  
Author(s):  
Vasishta Bhargava ◽  
Rahul Samala
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Power Level ◽  
Turbine Blades ◽  
Acoustic Emissions ◽  
Aerodynamic Noise ◽  
Sound Power ◽  
Wind Turbine Blades ◽  
Blade Length ◽  
Noise Production

Research on broadband aerodynamic noise from wind turbine blades is becoming important in several countries. In this work, computer simulation of acoustic emissions from wind turbine blades are predicted using quasi empirical model for a three-bladed horizontal axis 3 MW turbine with blade length ~47 m. Sound power levels are investigated for source and receiver height of 80 m and 2 m above ground and located at a distance equal to total turbine height. The results are validated using existing experimental data for Siemens SWT-2.3 MW turbine having blade length of 47 m, as well as with 2.5 MW turbine. Aerofoil self-noise mechanisms are discussed in present work and results are demonstrated for wind speed of 8 m/s. Overall sound power levels for 3 MW turbine showed good agreements with the existing experiment data obtained for SWT-2.3 MW turbine. Noise map of single source sound power level, dBA of an isolated blade segment located at 75 %R for single blade is illustrated for wind speed of 8 m/s. The results demonstrated that most of the noise production occurred from outboard section of blade and for blade azimuth positions between 80° and 170°.

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.

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