Performance Studies on a Wind Turbine Blade Section for Low Wind Speeds With a Gurney Flap

The flow characteristics and the lift and drag behavior of a thick trailing-edged airfoil that was provided with fixed trailing-edge flaps (Gurney flaps) of 1–5% height right at the back of the airfoil were studied both experimentally and numerically at different low Reynolds numbers (Re) and angles of attack for possible applications in wind turbines suitable for the wind speeds of 4–6 m/s. The flap considerably improves the suction on the upper surface of the airfoil resulting in a higher lift coefficient. The drag coefficient also increased; however, the increase was less compared with the increase in the lift coefficient, resulting in a higher lift-to-drag ratio in the angles of attack of interest. The results show that trailing-edge flaps can improve the performance of blades designed for low wind speeds and can be directly applied to small wind turbines that are increasingly being used in remote places or in smaller countries.

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Performance Improvement of a Wind Turbine Blade Designed for Low Wind Speeds With a Passive Trailing Edge Flap

Volume 6: Energy, Parts A and B ◽

10.1115/imece2012-88417 ◽

2012 ◽

Author(s):

Mohammed Rafiuddin Ahmed ◽

Epeli Nabolaniwaqa

Keyword(s):

Wind Turbines ◽

Lift Coefficient ◽

Leading Edge ◽

Adverse Pressure Gradient ◽

Suction Surface ◽

Trailing Edge ◽

Wind Speeds ◽

Trailing Edge Flaps ◽

Low Wind Speeds ◽

Lift And Drag

The flow characteristics and the lift and drag behavior of a newly designed thick trailing-edged airfoil that was provided with fixed trailing edge flaps (Gurney flaps) of 1% to 5% height right at the back of the airfoil were studied at different low Reynolds numbers (Re) and angles of attack for possible applications in wind turbines suitable for the wind speeds of 4–6 m/s that are common in the Pacific Island Countries. A thick trailing-edged blade section, AF300, that was designed and tested in a recent work for small horizontal axis wind turbines to improve the turbine’s startup and performance at low wind speeds was chosen for this study. Experiments were performed on the AF300 airfoil in a wind tunnel at different Re, flap heights and angles of attack. Pressure distributions were obtained across the surface of the airfoil and the lift and drag forces were measured for different cases. It was found that the flap considerably improves the suction on the upper surface of the airfoil resulting in a high lift coefficient. For some of the angles, in the case of 3 mm and 4 mm flaps, the peak Cp values on the suction surface were significantly higher compared to those without the flap. However, at angles of attack of 12° and above, this unusually high Cp on the upper surface close to the leading edge caused flow separation for some cases as the flow could not withstand the strong adverse pressure gradient. The CFX results matched most of the experimental results without flaps, except that the suction peak was lower numerically. The difference was higher for the case with flaps. It is clear from the results that trailing-edge flaps can be used to improve the performance of small wind turbines designed for low wind speeds.

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The effect of gurney flap on flow characteristics of vertical axis wind turbine

International Journal of Modern Physics B ◽

10.1142/s0217979220401074 ◽

2020 ◽

Vol 34 (14n16) ◽

pp. 2040107

Author(s):

Taurista Perdana Syawitri ◽

Yu-Feng Yao ◽

Jun Yao ◽

Budi Chandra

Keyword(s):

Wind Turbine ◽

Lift Coefficient ◽

Flow Characteristics ◽

Vertical Axis ◽

Vertical Axis Wind Turbine ◽

Horizontal Axis Wind Turbine ◽

Trailing Edge ◽

Eddy Simulation ◽

Moment Coefficient ◽

Gurney Flap

Recently, the Gurney Flap (GF) has been used to improve the performance of Horizontal Axis Wind Turbine (HAWT) by enhancing its lift coefficient. Compared to HAWT, research on GF application for Vertical Axis Wind Turbine (VAWT) is very limited. Moreover, most works studied a GF geometry attached to the trailing edge of a stationary airfoil, without considering the rotating effect experienced by VAWT. For this reason, a three-straight-bladed VAWT rotating blade with GF is studied by transient RANS simulation together with a stress-blended eddy simulation (SBES) turbulence model to investigate the GF height effect and the flow characteristics near the blade trailing edge. Results have shown that by introducing the blade rotating, an optimum GF height is found to be 3% of the blade chord, slightly higher than 2% chord in a stationary airfoil case. In addition, the presence of GF can delay deep stall of VAWT blades, thus eliminating negative instantaneous moment coefficient and improving the turbine performance.

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A Parametric Study of Trailing Edge Flap Implementation on Three Different Airfoils Through an Artificial Neuronal Network

Symmetry ◽

10.3390/sym12050828 ◽

2020 ◽

Vol 12 (5) ◽

pp. 828

Author(s):

Igor Rodriguez-Eguia ◽

Iñigo Errasti ◽

Unai Fernandez-Gamiz ◽

Jesús María Blanco ◽

Ekaitz Zulueta ◽

...

Keyword(s):

Aerodynamic Coefficients ◽

Trailing Edge ◽

High Lift ◽

Trailing Edge Flaps ◽

Artificial Neural Network Ann ◽

Lift And Drag ◽

Artificial Neuronal Network ◽

Naca 0012 ◽

Drag Ratio ◽

Lift To Drag Ratio

Trailing edge flaps (TEFs) are high-lift devices that generate changes in the lift and drag coefficients of an airfoil. A large number of 2D simulations are performed in this study, in order to measure these changes in aerodynamic coefficients and to analyze them for a given Reynolds number. Three different airfoils, namely NACA 0012, NACA 64(3)-618, and S810, are studied in relation to three combinations of the following parameters: angle of attack, flap angle (deflection), and flaplength. Results are in concordance with the aerodynamic results expected when studying a TEF on an airfoil, showing the effect exerted by the three parameters on both aerodynamic coefficients lift and drag. Depending on whether the airfoil flap is deployed on either the pressure zone or the suction zone, the lift-to-drag ratio, CL/CD, will increase or decrease, respectively. Besides, the use of a larger flap length will increase the higher values and decrease the lower values of the CL/CD ratio. In addition, an artificial neural network (ANN) based prediction model for aerodynamic forces was built through the results obtained from the research.

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Pengaruh diameter dan jumlah sudu turbin angin savonius tipe L terhadap unjuk kerja yang dihasilkan

ARMATUR : Artikel Teknik Mesin & Manufaktur ◽

10.24127/armatur.v1i2.333 ◽

2020 ◽

Vol 1 (2) ◽

pp. 61-67

Author(s):

Mohammad Rizqi Saputra ◽

Nur Kholis ◽

Mohammad Munib Rosadi

Keyword(s):

Energy Source ◽

Wind Turbine ◽

Wind Turbines ◽

Mechanical Energy ◽

Simulation Method ◽

Wind Speeds ◽

Turbine Efficiency ◽

Analysis Technique ◽

Low Wind Speeds ◽

Wind Source

Abstract Wind is a renewable mechanical energy source that can be used as an energy source because the energy from the wind can be used to drive wind turbines. Savonius wind turbine type L is a tool to convert wind energy into electricity with a simple construction and can work with low wind speeds. The purpose of this study was to determine the effect of differences in diameter and number of blades on the power produced. The method used is a simulation method with an artificial wind source. With a wind speed of 8 m/s. The data analysis technique used is 2-way ANOVA using the SPSS application. Variations used are 20 cm and 40 cm in diameter and the number of blades 2 and 4 . The result is a wind turbine with a variation of 40 cm and 4 blades capable of producing the best output which produces 350.98 RPM voltage of 11.64 volts current of 0.144 amperes and power of 1,676 watts. As for BHP, torque, and turbine efficiency with a variation of 40 cm and 4 blades capable of producing the best output where the generated BHP is 3.352 watts, torque 0.091 N / m efficiency 2.17. For the results of calculations with SPSS wind turbines with a diameter variation of 40 cm and 4 blades, the biggest power is 1,744 watts and for BHP produces 3.3520 watts and the efficiency reaches 2.17%. Keyword : Diameter, number of blade, Performance Abstrak Angin adalah sumber energi mekanik yang bisa diperbaharui sehingga dapat dimanfaatkan sebagai sumber energi karena dapat digunakan untuk menggerakkan turbin angin. Turbin angin savonius tipe L merupakan alat untuk mengubah energi angin menjadi listrik dengan konstruksi yang sederhana dan dapat bekerja dengan kecepatan angin yang rendah. Tujuan penelitian ini untuk mengetahui pengaruh perbedaan diameter dan jumlah sudu terhadap unjuk kerja yang dihasilkan. Metode yang digunakan adalah metode simulasi dengan sumber angin buatan. Dengan kecepatan angin 8 m/s. Teknik analisis data yang digunakan adalah ANOVA 2 arah dengan menggunakan aplikasi SPSS. Variasi yang digunakan adalah diameter 20 cm dan 40 cm serta jumlah sudu 2 dan 4. Hasilnya turbin angin dengan variasi 40 cm dan 4 sudu mampu menghasilkan output terbaik yang dimana menghasilkan RPM 350,98 tegangan 11,64 volt arus 0,144 ampere dan daya 1,676 watt. Sedangkan untuk BHP, torsi, dan efisensi turbin dengan variasi 40 cm dan 4 sudu mampu menghasilkan output yang terbaik dimana BHP yang dihasilkan adalah 3,352 watt, torsi 0,091 N/m efisisensi 2,17. Untuk hasil perhitungan dengan SPSS turbin angin dengan variasi diameter 40 cm dan 4 sudu menghasilkan daya terbesar yakni 1,744 watt dan untuk BHP menghasilkan 3,3520 watt dan efisiensinya mencapai 2,17 % untuk torsi tertinggi dicapai turbin variasi 40 cm 2 sudu dengan torsi 0,116. Kata kunci : diameter, jumlah sudu, unjuk kerja

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Elliptic Airfoil Stall Analysis With Trailing Edge Slots

Volume 1: Advances in Aerospace Technology ◽

10.1115/imece2010-38606 ◽

2010 ◽

Author(s):

Jonathan Kweder ◽

Mary Ann Clarke ◽

James E. Smith

Keyword(s):

Lift Coefficient ◽

Leading Edge ◽

Surface Velocity ◽

Circulation Control ◽

West Virginia University ◽

Trailing Edge ◽

Near Surface ◽

Wind Speeds ◽

Edge Location ◽

Stall Angle

Circulation control (CC) is a high-lift methodology that can be used on a variety of aerodynamic applications. This technology has been in the research and development phase for over sixty years primarily for fixed wing aircraft where the early models were referred to as “blown flaps”. Circulation control works by increasing the near surface velocity of the airflow over the leading edge and/or trailing edge of a lifting surface This phenomenon keeps the boundary layer jet attached to the wing surface thus increasing the lift generated on the surface. The circulation control airflow adds energy to the lift force through conventional airfoil lift production and by altering the circulation of stream lines around the airfoil. For this study, a 10:1 aspect ratio elliptical airfoil with a chord length of 11.8 inches and a span of 31.5 inches was inserted into the West Virginia University Closed Loop Wind Tunnel and was tested at varying wind speeds (80, 100, and 120 feet per second), angle of attack (zero to sixteen degrees), and blowing coefficients, ranging from 0.0006 to 0.0127 depending on plenum pressure. By comparing the non-circulation controlled wing with the active circulation control data, a trend was found as to the influence of circulation control on the stall characteristics of the wing for trailing edge active control. For this specific case, when the circulation control is in use on the 10:1 elliptical airfoil, the stall angle decreased, from eight degrees to six degrees, while providing a 70% increase in lift coefficient. It should be noted that due to the trailing edge location of the circulation control exit jet, a “virtual” camber is created with the free stream air adding length to the overall airfoil. Due to this phenomena, the actual stall angle measured increased from eight degrees on the un-augmented airfoil, to a maximum of twelve degrees.

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Effect of Slotted Angle on Savonius Wind Turbine Performance

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.104.83 ◽

2021 ◽

Vol 104 ◽

pp. 83-88

Author(s):

Rahmat Wahyudi ◽

Diniar Mungil Kurniawati ◽

Alfian Djafar

Keyword(s):

Wind Energy ◽

Wind Turbine ◽

Wind Turbines ◽

Electrical Energy ◽

Speed Ratio ◽

Angle Variation ◽

Wind Speeds ◽

Turbine Performance ◽

Savonius Wind Turbine ◽

Low Wind Speeds

The potential of wind energy is very abundant but its utilization is still low. The effort to utilize wind energy is to utilize wind energy into electrical energy using wind turbines. Savonius wind turbines have a very simple shape and construction, are inexpensive, and can be used at low wind speeds. This research aims to determine the effect of the slot angle on the slotted blades configuration on the performance produced by Savonius wind turbines. Slot angle variations used are 5o ,10o , and 15o with slotted blades 30% at wind speeds of 2,23 m/s to 4,7 m/s using wind tunnel. The result showed that a small slot angle variation of 5o produced better wind turbine performance compared to a standard blade at low wind speeds and a low tip speed ratio.

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Optimal Design of a Smart Conformable Rotor Airfoil

Adaptive Structures and Materials Systems ◽

10.1115/imece2002-39030 ◽

2002 ◽

Cited By ~ 2

Author(s):

Roberto A. Sarjeant ◽

Mary Frecker ◽

Farhan S. Gandhi

Keyword(s):

Lift Coefficient ◽

Vibration Reduction ◽

Active Material ◽

Optimization Method ◽

Skin Thickness ◽

Optimization Approach ◽

Trailing Edge ◽

Element Analysis ◽

Aerodynamic Loads ◽

Trailing Edge Flaps

An optimization method has been developed for the design of a smart conformable rotor airfoil with distributed piezoelectric actuators. A conformable airfoil is proposed as a substitute for trailing edge flaps used for helicopter vibration reduction by achieving high frequency camber variations. A topology optimization approach is used where the objective is to maximize trailing edge deflection while minimizing airfoil deformations due to aerodynamic loads. Solutions of the design problem are obtained using Sequential Linear Programming coupled with a Finite Element Analysis procedure. Results show good algorithm convergence and satisfactory airfoil deformations. A study of the effects of different active material resources, skin thickness and aerodynamic loads is performed. Changes in lift coefficient are found to be lower than those obtained for an equivalent flap at similar deflection angles, suggesting that larger deflections might be required for vibration reduction purposes.

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The Effect of Gurney Flap and Trailing-edge Wedge on the Aerodynamic Behavior of an Axial Turbine Blade

HighTech and Innovation Journal ◽

10.28991/hij-2021-02-04-03 ◽

2021 ◽

Vol 2 (4) ◽

pp. 293-305

Author(s):

Mohammad Mahdi Mahzoon ◽

Masoud Kharati-Koopaee

Keyword(s):

Angle Of Attack ◽

Vortex Generator ◽

Aerodynamic Performance ◽

Trailing Edge ◽

Blunt Trailing Edge ◽

Gurney Flap ◽

Maximum Increment ◽

Lift And Drag ◽

Lift And Drag Coefficient

In this research, the effect of Gurney flap and trailing-edge wedge on the aerodynamic behavior of blunt trailing-edge airfoil Du97-W-300 which is equipped with vortex generator is studied. To do this, the role of Gurney flap and trailing-edge wedge on the lift and drag coefficient and also aerodynamic performance of the airfoil is studied. Validation of the numerical model is performed by comparison of the obtained results with those of experiment. Results show that before stall, Gurney flap leads to the increase in the aerodynamic performance in a wider range of angle of attack. Numerical findings reveal that the maximum increment for the aerodynamic performance is obtained at low angle of attack when trailing-edge wedge is employed. It is found that for the highest considered value of Gurney flap and trailing-edge wedge heights, where the highest values for the lift occur, the higher aerodynamic performance at low angle of attack is obtained when trailing-edge wedge is used and at high angle of attack, the Gurney flap results in a higher aerodynamic performance. It is also shown that when high aerodynamic performance is concerned, addition of Gurney flap to the airfoil leads to the higher value for the lift. Doi: 10.28991/HIJ-2021-02-04-03 Full Text: PDF

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Numerical Modeling of the Effects of Leading-Edge Erosion and Trailing-Edge Damage on Wind Turbine Loads and Performance

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4048451 ◽

2020 ◽

Vol 142 (11) ◽

Author(s):

Francesco Papi ◽

Lorenzo Cappugi ◽

Sebastian Perez-Becker ◽

Alessandro Bianchini

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Prolonged Exposure ◽

Leading Edge ◽

Future Generation ◽

Operating Conditions ◽

Wind Speeds ◽

And Performance ◽

Lift And Drag ◽

The Impact

Abstract Wind turbines operate in challenging environmental conditions. In hot and dusty climates, blades are constantly exposed to abrasive particles that, according to many field reports, cause significant damages to the leading edge. On the other hand, in cold climates similar effects can be caused by prolonged exposure to hail and rain. Quantifying the effects of airfoil deterioration on modern multi-MW wind turbines is crucial to correctly schedule maintenance and to forecast the potential impact on productivity. Analyzing the impact of damage on fatigue and extreme loading is also important to improve the reliability and longevity of wind turbines. In this work, a blade erosion model is developed and calibrated using computational fluid dynamics (CFD). The Danmarks Tekniske Universitet (DTU) 10 MW Reference Wind Turbine is selected as the case study, as it is representative of the future generation wind turbines. Lift and Drag polars are generated using the developed model and a CFD numerical setup. Power and torque coefficients are compared in idealized conditions at two wind speeds, i.e., the rated speed and one below it. Full aero-servo-elastic simulations of the turbine are conducted with the eroded polars using NREL's BEM-based code OpenFAST. Sixty-six 10-min simulations are performed for each stage of airfoil damage, reproducing operating conditions specified by the IEC 61400-1 power production DLC-group, including wind shear, yaw misalignment, and turbulence. Aeroelastic simulations are analyzed, showing maximum decreases in CP of about 12% as well as reductions in fatigue and extreme loading.

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