EXPERIMENTAL EVALUATION OF THE AERODYNAMIC PERFORMANCE OF SMALL WIND TURBINES CONFECTIONED IN 3D PROTOTYPING

This paper presents the experimental evaluation of the aerodynamic performance of two small wind turbines models with five blades in the Aerodynamic Tunnel Professor Debi Pada Sadhu. The models were confectioned on a reduced scale using 3D prototyping, the first one was designed using the blade element method, assuming the power coefficient of Betz, named Optimal Blade Betz (OBB) and the second is modified from the first one, named Optimal Blade Betz Modified (OBBM). The velocity distribution in the cross section of the tunnel was determined with the aid of a Pitot tube before the evaluation of the equipment. With the known tunnel velocity profile, the static torque of the prototypes were determined with the use of a digital torquemeter coupled to the machine axis, which recorded the readings for the speed range of 1 m/s to 9.88 m/s. Also with the torquemeter, were evaluated the influence of the angular position of the blades in the measured torque. The blades were designed allowing vary their angular position in the hub, thus changing the angle of attack, and by consequence, the torque produced. A photo tachometer was employed to measure the rotation of the model in free spin. With the experimental data, the curves of static torque and angular velocity were determined as a function of incident speed. Through experimental determination of the incident velocity profile and the velocity profile in the aerodynamic wake of each turbine, the variation of the amount of momentum of the outflow was evaluated, and so the power extracted by the rotor in free rotation. This study aims to contribute to the design of a real small wind turbine, informing the aerodynamic characteristics of the equipment that can be constructed with this layout. The experimental results demonstrate good approximation for torque and power to the results obtained by evaluation by element of the blade method. The turbine constructed with Optimal Betz Blades presented static torque 17.8% higher than constructed with the Modified Blades and extracted 22% more power from the air outflow.

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A comprehensive comparative investigation of the Lifting Line Theory and Blade Element Momentum Theory applied to small wind turbines

Journal of Energy Resources Technology ◽

10.1115/1.4053066 ◽

2021 ◽

pp. 1-25

Author(s):

K.A.R. Ismail ◽

Willian Okita

Keyword(s):

Wind Turbines ◽

Power Coefficient ◽

Computational Time ◽

Local Flow ◽

Small Wind Turbines ◽

Wake Effects ◽

Line Theory ◽

Lifting Line ◽

Lifting Line Theory ◽

Blade Element

Abstract Small wind turbines are adequate for electricity generation in isolated areas to promote local expansion of commercial activities and social inclusion. Blade element momentum (BEM) method is usually used for performance prediction, but generally produces overestimated predictions since the wake effects are not precisely accounted for. Lifting line theory (LLT) can represent the blade and wake effects more precisely. In the present investigation the two methods are analyzed and their predictions of the aerodynamic performance of small wind turbines are compared. Conducted simulations showed a computational time of about 149.32 s for the Gottingen GO 398 based rotor simulated by the BEM and 1007.7 s for simulation by the LLT. The analysis of the power coefficient showed a maximum difference between the predictions of the two methods of about 4.4% in the case of Gottingen GO 398 airfoil based rotor and 6.3% for simulations of the Joukowski J 0021 airfoil. In the case of the annual energy production a difference of 2.35% is found between the predictions of the two methods. The effects of the blade geometrical variants such as twist angle and chord distributions increase the numerical deviations between the two methods due to the big number of iterations in the case of LLT. The cases analyzed showed deviations between 3.4% and 4.1%. As a whole, the results showed good performance of both methods; however the lifting line theory provides more precise results and more information on the local flow over the rotor blades.

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Optimal Design of Wind Turbines Using BIAS, A Method of Multipliers Code

14th Design Automation Conference ◽

10.1115/detc1988-0026 ◽

1988 ◽

Author(s):

B. D. Vick ◽

W. Wrigglesworth ◽

L. B. Scott ◽

K. M. Ragsdell

Keyword(s):

Optimal Design ◽

Rough Surface ◽

Wind Turbines ◽

Lift Coefficient ◽

Power Coefficient ◽

Method Of Multipliers ◽

High Lift ◽

Small Wind Turbines ◽

Drag Ratio ◽

Lift To Drag Ratio

Abstract A method has been developed and is demonstrated which determines the chord and twist distribution for a wind turbine with maximum power coefficient. Only small wind turbines (less than 10 kilowatts) are considered in this study, but the method could be used for larger wind turbines. Glauert determined a method for estimating the chord and twist distribution that will maximize the power coefficient if there is no drag. However, the method proposed here determines the chord and twist distribution which will maximize the power coefficient with the effect of drag included. Including drag in the analysis does not significantly affect the Glauert chord and twist distribution for airfoils with a high lift coefficient at the maximum lift to drag ratio. However, if the airfoil has a fairly low lift coefficient at its maximum lift to drag ratio due to its shape or a rough surface then significant improvement can be obtained in power coefficient by altering the Glauert chord and twist distribution according to the method proposed herein.

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Strategic Blade Shape Optimization for Aerodynamic Performance Improvement of Wind Turbines

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2016-56836 ◽

2016 ◽

Cited By ~ 1

Author(s):

Youjin Kim ◽

Ali Al-Abadi ◽

Antonio Delgado

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Optimization Methods ◽

Turbine Rotor ◽

Aerodynamic Performance ◽

Power Coefficient ◽

Speed Ratio ◽

Blade Shape ◽

Improved Design ◽

Wind Turbine Rotor

This study introduces strategic methods for improving the aerodynamic performance of wind turbines. It was completed by combining different optimization methods for each part of the wind turbine rotor. The chord length and pitch angle are optimized by a torque-matched method (TMASO), whereas the airfoil shape is optimized by the genetic algorithm (GA). The TMASO is implemented to produce an improved design of a reference turbine (NREL UAE Phase V). The GA is operated to generate a novel airfoil design that is evaluated by automatic interfacing for the highest gliding ratio (GR). The adopted method produces an optimized wind turbine with an 11% increase of power coefficient (Cp) with 30% less of the corresponding tip speed ratio (TSR). Furthermore, the optimized wind turbine shows reduced tip loss effect.

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Improvement of Aerodynamic Performance of Savonius Wind Rotor Using Straight-Arc Curtain

Applied Sciences ◽

10.3390/app10207216 ◽

2020 ◽

Vol 10 (20) ◽

pp. 7216

Author(s):

Hongfu Zhang ◽

Zhiqiang Li ◽

Dabo Xin ◽

Jian Zhan

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Flow Field ◽

Aerodynamic Performance ◽

Power Coefficient ◽

Mean Power ◽

Negative Moment ◽

Dynamic Performances ◽

Dynamics Method ◽

Static Torque

A straight and an arc-shaped curtain are combined to enhance the aerodynamic performance of the Savonius wind rotor. The straight-arc curtain is placed in front of the Savonius wind rotor to reduce the negative moment on the convex blade and increase the positive moment on the concave blade. The static and dynamic performances of the Savonius wind rotor with and without the curtain are investigated based on the computational fluid dynamics method. The results show that the static torque is higher with the curtain than without it at the same angle-of-attack. The maximum mean power coefficient with the curtain is increased by about 50% compared with conventional Savonius wind rotor. Additionally, the flow field around the rotor with the straight-arc curtain is presented, and the flow control mechanics of the straight-arc curtain are discussed.

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Improvement of Aerodynamic Performance and Energy Supply of Bridges Using Small Wind Turbines

Journal of Bridge Engineering ◽

10.1061/(asce)be.1943-5592.0000727 ◽

2015 ◽

Vol 20 (10) ◽

pp. 04014116 ◽

Cited By ~ 2

Author(s):

Seungho Lee ◽

Soon-Duck Kwon

Keyword(s):

Wind Turbines ◽

Energy Supply ◽

Aerodynamic Performance ◽

Small Wind Turbines

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Performance of Crossflow Wind Turbines in In-line Configuration and Opposite Rotation Direction

Journal of Advanced Research in Fluid Mechanics and Thermal Sciences ◽

10.37934/arfmts.81.1.131139 ◽

2021 ◽

Vol 81 (1) ◽

pp. 131-139

Author(s):

Zainal Arifin ◽

Dominicus Danardono Dwi Prija Tjahjana ◽

Suyitno Suyitno ◽

Wibawa Endra Juwana ◽

Rendhy Adhi Rachmanto ◽

...

Keyword(s):

Wind Turbines ◽

Turbine Blades ◽

Performance Testing ◽

Electrical Energy ◽

Low Noise ◽

Power Coefficient ◽

Rotation Direction ◽

Turbine Performance ◽

Line Configuration ◽

Small Wind Turbines

Wind energy sources must be investigated to produce electrical energy from a renewable source. Crossflow wind turbines are suitable for use because they have several advantages such as self-starting ability, low noise, and excellent stability. They have the potential to be applied as small wind turbines in urban districts because of their small maximum coefficient of power (Cp), which is 10% of that of other small wind turbines. To enhance the performance of crossflow wind turbines, we changed the turbine to rotate in the opposite direction in the in-line configuration. Turbine performance testing was tested using a wind tunnel. The characteristics of crossflow wind turbines were investigated, then turbine performance was analyzed and discussed. The maximum power coefficient obtained was 0.169 (Cp) with the configuration of 12 turbine blades at a wind speed of 10 m/s. The maximum torque coefficient obtained was 0.703. The overall results show that the crossflow wind turbine in in-line configuration with opposite rotation can improve the performance of wind turbines.

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Aerodynamic performance of bridges equipped small wind turbines

Dynamics of Bridges, Volume 5 - Conference Proceedings of the Society for Experimental Mechanics Series ◽

10.1007/978-1-4419-9825-5_9 ◽

2011 ◽

pp. 85-92 ◽

Cited By ~ 1

Author(s):

Soon-Duck Kwon ◽

Seung-Ho Lee ◽

Han Kyu Lee

Keyword(s):

Wind Turbines ◽

Aerodynamic Performance ◽

Small Wind Turbines

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STUDY ON AERODYNAMIC PERFORMANCE OF THE BIONIC AIRFOIL BASED ON THE SWALLOW'S WING

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519413400228 ◽

2013 ◽

Vol 13 (06) ◽

pp. 1340022 ◽

Cited By ~ 2

Author(s):

WEIJUN TIAN ◽

FANGYUAN LIU ◽

QIAN CONG ◽

YURONG LIU ◽

LUQUAN REN

Keyword(s):

Wind Tunnel ◽

Wind Turbines ◽

Lift Coefficient ◽

Angle Of Attack ◽

Aerodynamic Performance ◽

Wind Tunnel Tests ◽

Small Wind Turbines ◽

Aerodynamic Performances ◽

Drag Ratio ◽

Bionic Airfoil

This paper demonstrates the design of the airfoil of small wind turbines, the bionic airfoil was inspired by the morphology of the swallow's extended wing. The wind tunnel tests on the bionic and standard airfoils NACA4412 were conducted, and the aerodynamic performances of the airfoils were numerically investigated. The results show that the bionic airfoil has better aerodynamic performance, the lift coefficient and lift-drag ratio are larger than those of the NACA4412; with the angle of attack increases, both the bionic and standard airfoils stall, but the stall characteristics of the bionic airfoil are better.

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A PROPOSED MATHEMATICAL MODEL FOR THE VELOCITY PROFILE INTERNALLY TO A CONICAL DIFFUSER

Revista de Engenharia Térmica ◽

10.5380/reterm.v12i2.62050 ◽

2013 ◽

Vol 12 (2) ◽

pp. 69

Author(s):

D. L. M. Barbosa ◽

D. A. T. D. R. Vaz ◽

J. R. P. Vaz ◽

S. W. O. Figueiredo ◽

M. O. Da Silva ◽

...

Keyword(s):

Mathematical Model ◽

Velocity Profile ◽

Wind Turbines ◽

Energy Flow ◽

Maximum Energy ◽

Power Coefficient ◽

Internal Mass ◽

Conical Diffuser ◽

Horizontal Axis Wind Turbines ◽

Good Agreement

The use of diffusers around of the horizontal-axis wind turbines have been widely studied, since the diffuser provides an improvement in the turbine power coefficient. These diffusers are often called Diffuser Augmented Wind Turbines (DAWT’s). The DAWT’s have the feature to make efficiency exceeding the Betz limit (maximum energy flow extracted = 59.26%), due to the increasing of the internal mass flow by influence of the diffuser presence. Thus, the present work proposed a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characteristics of flow and geometry of a conical diffuser. The model results were compared with experimental data and showed good agreement.

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