Effects of the airfoil section, chord and twist angle distributions on the starting torque of small horizontal axis wind turbines

2021 ◽  
pp. 1-23
Author(s):  
K.A.R. Ismail ◽  
Thiago Canale ◽  
Fatima M. Lino
Keyword(s):  
Wind Speed ◽  
Wind Turbines ◽  
Twist Angle ◽  
Numerical Code ◽  
Angle Distribution ◽  
Blade Length ◽  
Wind Speeds ◽  
Solidity Ratio ◽  
Small Wind Turbines ◽  
Starting Torque

Abstract Small wind turbines usually suffer from poor efficincy, low power and lack of public incentives. This study is focused on investigating the effects of the geometry of the airfoil sections and blades on the starting torque and minimum wind speed for energy generation. The Blade Element Momentum Theory is used to develop a numerical code where the airfoil S832 is used as a reference for comparison and validation. The investigated parameters include three airfoil sections Joukowski J9.513, Gottingen GO447, and S832, linear and elliptic chord distributions, linear twist angle distribution and multiple airfoil sections along the blade. The results show that large local solidity ratio at the intermediate region of elliptic chord distribution produces significant reduction in the local generated torque of about 5-21% and that the linear chord distribution along the blade length increases the torque by about 27-77% and thus permits lower starting wind speeds. For rotors with high solidity ratio as in the case of elliptic chord distribution, the distribution of twist angle for constant angle of attack reduces the generated torque by about 13-19%. The J9.513 airfoil based rotor shows 20-35% more start torque than the S832 and GO447 airfoils based rotors. The linear chord distribution is shows better results for all the three airfoils based rotors. The linear twist angle distribution increases significantly the start torque of the rotors with the proposed airfoils sections. The three airfoils S832, GO447 and J9.513with linear twist angle distribution are viable options for small wind turbines. The J9.513 with linear chord and linear twist angle distribution shows the lowest wind speed for electricity generation. The use of multiple airfoils on the blade length shows marginal improvement of the starting torque.

scholarly journals Pitch Angle Optimization by Intelligent Adjusting the Gains of a PI Controller for Small Wind Turbines in Areas with Drastic Wind Speed Changes

2019 ◽  
Vol 11 (23) ◽  
pp. 6670
Author(s):  
Ernesto Chavero-Navarrete ◽  
Mario Trejo-Perea ◽  
Juan-Carlos Jáuregui-Correa ◽  
Roberto-Valentín Carrillo-Serrano ◽  
José-Gabriel Rios-Moreno
Keyword(s):  
Wind Speed ◽  
Wind Turbines ◽  
Pitch Angle ◽  
Sudden Change ◽  
Stable State ◽  
Synchronous Generator ◽  
Longitudinal Axis ◽  
Wind Speeds ◽  
Main Challenge ◽  
Small Wind Turbines

The population growth demands a greater generation of energy, an alternative is the use of small wind turbines, however, obtaining maximum wind power becomes the main challenge when there are drastic changes in wind speed. The angle of the blades rotates around its longitudinal axis to control the effect of the wind on the rotation of the turbine, a proportional-integral controller (PI) for this angle achieves stability and precision in a stable state but is not functional with severe alterations in wind speed, a different response time is necessary in both cases. This article proposes a novel pitch angle controller based on auto-tuning of PI gains, for which it uses a teaching–learning based optimization (TLBO) algorithm. The wind speed and the value of the magnitude of the change are used by the algorithm to determine the appropriate PI gains at different wind speeds, so it can adapt to any sudden change in wind speed. The effectiveness of the proposed method is verified by experimental results for a 14 KW permanent magnet synchronous generator (PMSG) wind turbine located at the Universidad Autónoma de Querétaro (UAQ), Mexico.

SHAPING OF AN AUTONOMOUS POWER SYSTEM FOR GUARANTEED POWER SUPPLY WITH THE PREDOMINANCE WIND ENERGY

2018 ◽  
pp. 28-50
Author(s):  
S. G. Ignatiev ◽  
S. V. Kiseleva
Keyword(s):  
Energy Storage ◽  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Demand ◽  
Diesel Generator ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Average Wind

Optimization of the autonomous wind-diesel plants composition and of their power for guaranteed energy supply, despite the long history of research, the diversity of approaches and methods, is an urgent problem. In this paper, a detailed analysis of the wind energy characteristics is proposed to shape an autonomous power system for a guaranteed power supply with predominance wind energy. The analysis was carried out on the basis of wind speed measurements in the south of the European part of Russia during 8 months at different heights with a discreteness of 10 minutes. As a result, we have obtained a sequence of average daily wind speeds and the sequences constructed by arbitrary variations in the distribution of average daily wind speeds in this interval. These sequences have been used to calculate energy balances in systems (wind turbines + diesel generator + consumer with constant and limited daily energy demand) and (wind turbines + diesel generator + consumer with constant and limited daily energy demand + energy storage). In order to maximize the use of wind energy, the wind turbine integrally for the period in question is assumed to produce the required amount of energy. For the generality of consideration, we have introduced the relative values of the required energy, relative energy produced by the wind turbine and the diesel generator and relative storage capacity by normalizing them to the swept area of the wind wheel. The paper shows the effect of the average wind speed over the period on the energy characteristics of the system (wind turbine + diesel generator + consumer). It was found that the wind turbine energy produced, wind turbine energy used by the consumer, fuel consumption, and fuel economy depend (close to cubic dependence) upon the specified average wind speed. It was found that, for the same system with a limited amount of required energy and high average wind speed over the period, the wind turbines with lower generator power and smaller wind wheel radius use wind energy more efficiently than the wind turbines with higher generator power and larger wind wheel radius at less average wind speed. For the system (wind turbine + diesel generator + energy storage + consumer) with increasing average speed for a given amount of energy required, which in general is covered by the energy production of wind turbines for the period, the maximum size capacity of the storage device decreases. With decreasing the energy storage capacity, the influence of the random nature of the change in wind speed decreases, and at some values of the relative capacity, it can be neglected.

scholarly journals Wind Turbulence Intensity at La Ventosa, Mexico: A Comparative Study with the IEC61400 Standards

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3007 ◽  
Author(s):  
C. Lopez-Villalobos ◽  
O. Rodriguez-Hernandez ◽  
R. Campos-Amezcua ◽  
Guillermo Hernandez-Cruz ◽  
O. Jaramillo ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Turbines ◽  
Turbulence Intensity ◽  
Structural Damage ◽  
Atmospheric Stability ◽  
Design Parameters ◽  
Power Sector ◽  
Wind Speeds ◽  
Technical Solutions ◽  
Large Wind

Wind speed turbulence intensity is a crucial parameter in designing the structure of wind turbines. The IEC61400 considers the Normal Turbulence Model (NTM) as a reference for fatigue load calculations for small and large wind turbines. La Ventosa is a relevant region for the development of the wind power sector in Mexico. However, in the literature, there are no studies on this important parameter in this zone. Therefore, we present an analysis of the turbulence intensity to improve the understanding of local winds and contribute to the development of reliable technical solutions. In this work, we experimentally estimate the turbulence intensity of the region and the wind shear exponent in terms of atmospheric stability to analyze the relation of these design parameters with the recommended standard for large and small wind turbines. The results showed that the atmosphere is strongly convective and stable in most of the eleven months studied. The turbulence intensity analysis showed that for a range of wind speeds between 2 and 24 m/s, some values of the variable measured were greater than those recommended by the standard, which corresponds to 388 hours of turbulence intensity being underestimated. This may lead to fatigue loads and cause structural damage to the technologies installed in the zone if they were not designed to operate in these wind speed conditions.

Analysis of Wind Field Fan Based on Performance Enhancement Method

2014 ◽  
Vol 986-987 ◽  
pp. 235-238
Author(s):  
Xiao Long Tan ◽  
Jia Zhou ◽  
Wen Bin Wang
Keyword(s):  
Wind Speed ◽  
Wind Turbines ◽  
Performance Enhancement ◽  
Aerodynamic Performance ◽  
Wind Load ◽  
Wind Speeds ◽  
Enhancement Method ◽  
Changes Over Time ◽  
Load Simulation ◽  
Single Constant

For the simulation of wind turbine, the wind speed is extremely important parameters and indicators to measure the output power of the unit is the wind load. Therefore, in the airflow dynamics and simulation of wind loads before establishing an accurate wind speed model is crucial. At present, the application for wind turbines COMSOL fan, fan blades and wind load simulation field, the extremely important wind speed model is not perfect, most of the research is confined to a single constant wind speed, wind speed virtually ignored the magnitude and direction of change, on changes over time and space at the same time is one of the few studies of wind, so find a way to accurately describe the range of wind speeds, and can be combined well with COMSOL method can greatly improve the aerodynamic performance of wind turbines the overall level of .

Comparative Study of New Airfoils for Small Horizontal Axis Wind Turbines

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Thiago Canale ◽  
Kamal A. R. Ismail ◽  
Fatima A. M. Lino ◽  
Ahmad Arabkoohsar
Keyword(s):  
Wind Turbines ◽  
Pitch Angle ◽  
High Efficiency ◽  
Twist Angle ◽  
Bending Moment ◽  
Poor Performance ◽  
Numerical Code ◽  
Power Coefficient ◽  
Intermediate Region ◽  
Marginal Improvement

Abstract The high cost and poor performance of small wind turbines make them not widely used. In an attempt to meliorate this situation, the authors propose to investigate alternative airfoils with different chord and pitch angle distributions that permit low manufacturing, installation and maintenance costs, as well as high efficiency. To achieve these goals, two airfoil sections, Gottingen and Joukowski, together with different chord and pitch angle distributions were simulated by using a validated numerical code based on the blade element momentum (BEM) method. The chord geometry includes constant, linear, and elliptic distributions while the twist angle includes constant and linear distributions. The results reveal that the linear pitch distribution reduces the thrust in the intermediate region of the blade and the bending moment at the root and reduces the power coefficient for both rotors. Rotors with elliptic chord distribution show increased forces in the intermediate region. Joukowski based blades with elliptic chord distribution show lower thrust compared with those with linear chord distribution. The linear chord distribution increases the thrust in the intermediate region and reduces it at the tip and root regions. Blades with multiple airfoils show marginal improvement. The Gottingen and Joukowski based rotors have similar annual energy production (AEP). The Joukowski based rotor with linear pitch and linear chord distribution shows better performance at low velocities and easy to manufacture which makes it a good candidate for small power wind turbines.

scholarly journals Analysis of the Patent of a Protective Cover for Vertical-Axis Wind Turbines (VAWTs): Simulations of Wind Flow

2020 ◽  
Vol 12 (18) ◽  
pp. 7818
Author(s):  
Jose Alberto Moleón Baca ◽  
Antonio Jesús Expósito González ◽  
Candido Gutiérrez Montes
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
High Speed ◽  
Experimental Tests ◽  
Weather Conditions ◽  
Vertical Axis ◽  
Good Alternative ◽  
Wind Speeds ◽  
Vertical Axis Wind Turbines

This paper presents a numerical and experimental analysis of the patent of a device to be used in vertical-axis wind turbines (VAWTs) under extreme wind conditions. The device consists of two hemispheres interconnected by a set of conveniently implemented variable section ducts through which the wind circulates to the blades. Furthermore, the design of the cross-section of the ducts allows the control of the wind speed inside the device. These ducts are intended to work as diffusers or nozzles, depending on the needs of the installation site. Simulations were performed for the case of high-speed external wind, for which the ducts act as diffusers to reduce wind speed and maintain a well-functioning internal turbine. Four different patent designs were analyzed, focusing on turbine performance and generated power. The results indicate that the patent allows the generation of electric power for a greater range of wind speeds than with a normal wind turbine. The results support that this patent may be a good alternative for wind power generation in geographic areas with extreme weather conditions or with maintained or strong gusty wind. Experimental tests were carried out on the movement of the blades using the available model. Finally, the power curve of the model of this wind turbine was obtained.

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 Small wind turbines study and integration in a peri-urban microgrid

2021 ◽  
Author(s):  
Paula Peña-Carro ◽  
Óscar Izquierdo-Monge ◽  
Luis Hernández-Callejo ◽  
Gonzalo Martín-Jiménez
Keyword(s):  
Wind Turbines ◽  
Urban Environments ◽  
Wind Speeds ◽  
Small Wind Turbines ◽  
Micro Power ◽  
The Cost ◽  
Wind Resource ◽  
Wind Resources ◽  
Selection Of ◽  
Instantaneous Control

The use of wind resources has always gone hand in hand with high wind speeds in open fields. This paper develops the decisions to be taken for the selection, installation, and connection of small wind turbines in peri-urban environments, where wind speeds are medium or low. The guidelines are detailed throughout the document, starting with the study of the wind resource, the selection of the turbine, installation, and real-time monitoring of production for integration into a micro power grid. The installation of small wind systems in places as close as possible to the point of demand makes it possible to achieve a reduction in the cost of the electricity bill. This is thanks to the instantaneous control of generation and demand at a particular level through the installation of software, in this case, Home Assistant. The novelty of this paper is the use of this software Home Assistant to integrate of a small wind turbine in a microgrid and its control system.

scholarly journals Results from a wake-steering experiment at a commercial wind plant: investigating the wind speed dependence of wake-steering performance

2021 ◽  
Vol 6 (6) ◽  
pp. 1427-1453
Author(s):  
Eric Simley ◽  
Paul Fleming ◽  
Nicolas Girard ◽  
Lucas Alloin ◽  
Emma Godefroy ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Direction ◽  
Wind Farm ◽  
Poor Performance ◽  
Power Production ◽  
Wind Rose ◽  
Wind Speeds ◽  
Variability Model

Abstract. Wake steering is a wind farm control strategy in which upstream wind turbines are misaligned with the wind to redirect their wakes away from downstream turbines, thereby increasing the net wind plant power production and reducing fatigue loads generated by wake turbulence. In this paper, we present results from a wake-steering experiment at a commercial wind plant involving two wind turbines spaced 3.7 rotor diameters apart. During the 3-month experiment period, we estimate that wake steering reduced wake losses by 5.6 % for the wind direction sector investigated. After applying a long-term correction based on the site wind rose, the reduction in wake losses increases to 9.3 %. As a function of wind speed, we find large energy improvements near cut-in wind speed, where wake steering can prevent the downstream wind turbine from shutting down. Yet for wind speeds between 6–8 m/s, we observe little change in performance with wake steering. However, wake steering was found to improve energy production significantly for below-rated wind speeds from 8–12 m/s. By measuring the relationship between yaw misalignment and power production using a nacelle lidar, we attribute much of the improvement in wake-steering performance at higher wind speeds to a significant reduction in the power loss of the upstream turbine as wind speed increases. Additionally, we find higher wind direction variability at lower wind speeds, which contributes to poor performance in the 6–8 m/s wind speed bin because of slow yaw controller dynamics. Further, we compare the measured performance of wake steering to predictions using the FLORIS (FLOw Redirection and Induction in Steady State) wind farm control tool coupled with a wind direction variability model. Although the achieved yaw offsets at the upstream wind turbine fall short of the intended yaw offsets, we find that they are predicted well by the wind direction variability model. When incorporating the expected yaw offsets, estimates of the energy improvement from wake steering using FLORIS closely match the experimental results.

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