The velocity of the tip vortex of a horizontal-axis wind turbine at high tip speed ratio

The present paper evaluates the tip vortex evolution of a horizontal axis wind turbine model using the stereo particle image velocimetry technology. The measurements of the wake region up to 2.7 diameters downstream are first conducted using the phase locked technique based on two high speed CCD cameras. Parameters that describe the helical vortex wake, such as the velocity, helicoidal pitch and vortex vorticity, are presented at two tip speed ratios. The vortex interaction and stability of helical vortex filaments within wind turbine wake are seen throughout the measurement domain. The results show the wake structure varies with tip speed ratio, and the helicoidal pitch of tip vortex trajectory reduces while the diffusion of tip vortex is faster with increasing tip speed ratio.

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Iterative Model for the Performance Evaluation of a Horizontal Axis Wind Turbine

Wind Engineering ◽

10.1260/030952402761699287 ◽

2002 ◽

Vol 26 (2) ◽

pp. 109-116

Author(s):

Sadhan Mahapatra ◽

Subhasis Neogi

Keyword(s):

Performance Evaluation ◽

Numerical Model ◽

Wind Turbine ◽

Horizontal Axis ◽

Speed Ratio ◽

Horizontal Axis Wind Turbine ◽

Tip Speed Ratio ◽

Iterative Model ◽

Flow Parameters ◽

Maximum Value

This paper is based on the studies made on a numerical model for calculating the turbine characteristics at low tip speed ratio for a Horizontal Axis Wind Turbine. The turbine characteristics are analysed for different configurations over the total operating range i.e. from tip speed ratio of zero to a maximum value where CP becomes zero. The simulation model provides acceptable results, however for the blade position near the hub, a non-convergent situation is observed i.e. the flow parameters converge to values outside those associated with turbine operation. This indicates the possibility of a multisolution.

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Aerodynamic Optimization of a Swept Horizontal Axis Wind Turbine Blade

Journal of Energy Resources Technology ◽

10.1115/1.4051469 ◽

2021 ◽

pp. 1-28

Author(s):

Mehmet Numan Kaya ◽

Faruk Köse ◽

Oguz Uzol ◽

Derek Ingham ◽

Lin Ma ◽

...

Keyword(s):

Wind Turbine ◽

Turbine Blade ◽

Wind Turbine Blade ◽

Horizontal Axis ◽

Power Coefficient ◽

Design Parameters ◽

Speed Ratio ◽

Blade Design ◽

Horizontal Axis Wind Turbine ◽

Tip Speed Ratio

Abstract The aerodynamic shapes of the blades are still of high importance and various aerodynamic designs have been developed in order to increase the amount of energy production. In this study, a swept horizontal axis wind turbine blade has been optimized to increase the aerodynamic efficiency using the Computational Fluid Dynamics method. To illustrate the technique, a wind turbine with a rotor diameter of 0.94 m has been used as the baseline turbine and the most appropriate swept blade design parameters, namely the sweep start up section, tip displacement and mode of the sweep have been investigated to obtain the maximum power coefficient at the design tip speed ratio. At this stage, a new equation that allows all three swept blade design parameters to be changed independently has been used to design swept blades, and the response surface method has been used to find out the optimum swept blade parameters. According to the results obtained, a significant increase of 4.28% in the power coefficient was achieved at the design tip speed ratio with the new designed optimum swept wind turbine blade. Finally, baseline and optimum swept blades have been compared in terms of power coefficients at different tip speed ratios, force distributions, pressure distributions and tip vortices.

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Design and optimization of a small horizontal axis wind turbine using BEM theory and tip loss corrections

E3S Web of Conferences ◽

10.1051/e3sconf/202129401003 ◽

2021 ◽

Vol 294 ◽

pp. 01003

Author(s):

Somaya Younoussi ◽

Abdeslem Ettaouil

Keyword(s):

Wind Turbine ◽

Horizontal Axis ◽

Power Coefficient ◽

Speed Ratio ◽

Optimization Approach ◽

Horizontal Axis Wind Turbine ◽

Newton’S Iterative Method ◽

Tip Speed Ratio ◽

De Vries ◽

Bem Theory

In this paper, an optimization approach of a small horizontal axis wind turbine based on BEM theory including De Vries and Shen et al. tip loss corrections is proposed. The optimal blade geometry was obtained by maximizing the power coefficient along the blade using the optimal angle of attack and the optimal tip speed ratio. The Newton’s iterative method applied to axial induction factor was used to solve the problem. This study was conducted for a NACA4418 small wind turbine, at low wind velocity. Among the two used tip loss corrections, the De Vries correction was found to be the most suitable for this blade optimization method. The optimal design was obtained for a tip speed ratio of 5 and has recorded a power coefficient equal to 0.463.

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Design and Fabrication of Small Horizontal axis wind Turbine Rotors at Low Reynolds Number

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.l3499.1081219 ◽

2019 ◽

Vol 8 (12) ◽

pp. 4454-4463 ◽

Cited By ~ 1

Keyword(s):

Reynolds Number ◽

Wind Turbine ◽

Low Reynolds Number ◽

Angle Of Attack ◽

Horizontal Axis ◽

Speed Ratio ◽

Horizontal Axis Wind Turbine ◽

Tip Speed Ratio ◽

Drag Ratio ◽

Lift To Drag Ratio

This research paper presents a design and fabrication of 100 Watt small horizontal axis wind turbine with 0.24 m and 0.35 m rotor radius and tip speed ratio varies from 2 to 10 was designed and development for operated at low wind speed with Low Reynolds number. In this paper, a new airfoil profile was designed and developed, it’s denoted by MK115. The numerical and experimental analysis for 6 airfoils using Xfoil software was conducted with a view to evaluating the lift-to-drag ratio and angle of attack by means of the SD7024, SG6043, NACA2412, S1210, E213, and New Airfoil (MK115) tested. In simulation, new MK115 airfoil was the most convenient airfoil to start high energy production for low-wind applications, on the Reynolds number 25000, 50000, 75000, and 100000 in improved airfoil (MK115) tests an Open type wind tunnel. An Xfoil analysis to obtain further data on the flow characteristics was also conducted. (MK115) airfoil have CLmax of 0.92, 1.25, 1.69, 1.67 at Re=25k, 50k, 75k and 100k for an angle of attack is equal to 100 .A maximum lift to drag ratio (Cl/Cd) of 7,16,50,63 at Re=25k, 50k, 75k and 100k for New airfoil (MK115) at angle of attack (α) =40 , 40 , 80 , 80 . SG6043, NACA2412, E214, SD7034, S1210 and MK115 (New airfoil) have the Maximum Cp=0.37, 0.36, 0.4, 0.39, 0.44, and 0.44 at tip speed ratio (λ) =6 for Reynolds number is equal to 100000. MK115, Maximum Torque obtained 0.9744 Nm, 1.389 Nm and 2.4866 Nm at blade angle =0, 15 and 30 degrees respectively. Power coefficient (Cp) =0.51, 0.5, 0.46, and 0.4 at Rotor shaft angle=00 , 50 , 100 , and 150 respectively for the new airfoil results.

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Solidity and Blade Number Effects on a Fixed Pitch, 50 W Horizontal Axis Wind Turbine

Wind Engineering ◽

10.1260/030952403322665271 ◽

2003 ◽

Vol 27 (4) ◽

pp. 299-316 ◽

Cited By ~ 10

Author(s):

Matthew M. Duquette ◽

Jessica Swanson ◽

Kenneth D. Visser

Keyword(s):

Wind Tunnel ◽

Wind Turbine ◽

Flat Plate ◽

Experimental Studies ◽

Horizontal Axis ◽

Optimum Operating ◽

Speed Ratio ◽

Horizontal Axis Wind Turbine ◽

Tip Speed Ratio ◽

Blade Number

Experimental studies were conducted on a modified Rutland 500 horizontal axis wind turbine to evaluate numerical implications of solidity and blade number on the aerodynamic performance. Wind tunnel data were acquired on the turbine with flat-plate, constant-chord blade sets and optimum-designed blade sets to compare with theoretical trends, which had indicated that increased solidity and blade number more than conventional 3-bladed designs, would yield larger power coefficients, CP. The data for the flat plate blades demonstrated power coefficient improvements as the range of solidities was increased from 7% to 27%, but did not indicate performance gains for increased blade numbers. It was also observed that larger pitch angles decreased the optimum tip speed ratio range significantly with a small (5% or less) change in maximum CP. The optimum-design 3-bladed rotors produced an increased experimental CP as solidity increased, with reduced tip speed ratio, at the optimum operating point. As blade number was increased at a constant solidity of 10% from 3 to 12 blades, aerodynamic efficiency and power sharply decreased, contrary to the numerical predictions and the flat plate experimental results. Low Reynolds numbers and wind tunnel blockage effects limit these conclusions and a full scale prototype rotor is being constructed to examine the results of the numerical and experimental studies using a side-by-side comparison with a commercially available wind turbine at the Clarkson University wind-turbine test site.

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An Experimental Study of the Aerodynamics and Performance of a Vertical Axis Wind Turbine in a Confined and Unconfined Environment

Journal of Energy Resources Technology ◽

10.1115/1.4030448 ◽

2015 ◽

Vol 137 (5) ◽

Cited By ~ 45

Author(s):

Vincenzo Dossena ◽

Giacomo Persico ◽

Berardo Paradiso ◽

Lorenzo Battisti ◽

Sergio Dell'Anna ◽

...

Keyword(s):

Experimental Study ◽

Wind Tunnel ◽

Wind Turbine ◽

Vertical Axis ◽

Tip Vortex ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Tip Speed Ratio ◽

And Performance ◽

Power Curves

This paper presents the results of a wide experimental study on an H-type vertical axis wind turbine (VAWT) carried out at the Politecnico di Milano. The experiments were carried out in a large-scale wind tunnel, where wind turbines for microgeneration can be tested in real-scale conditions. Integral torque and thrust measurements were performed, as well as detailed aerodynamic measurements to characterize the flow field generated by the turbine downstream of the rotor. The machine was tested in both a confined (closed chamber) and unconfined (open chamber) environment, to highlight the effect of wind tunnel blockage on the aerodynamics and performance of the VAWT under investigation. The experimental results, compared with the blockage correlations presently available, suggest that specific correction models should be developed for VAWTs. The experimental thrust and power curves of the turbine, derived from integral measurements, exhibit the expected trends with a peak power coefficient of about 0.28 at tip-speed ratio equal to 2.5. Flow measurements, performed in three conditions for tip speed ratio equal to 1.5, 2.5, and 3.5, show the fully three-dimensional character of the wake, especially in the tip region where a nonsymmetrical wake and tip vortex are found. The unsteady evolution of the velocity and turbulence fields further highlights the effect of aerodynamic loading on the wake unsteadiness, showing the time-dependent nature of the tip vortex and the onset of dynamic stall for tip speed ratio lower than 2.

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A Simplified Free Wake Method for Horizontal-Axis Wind Turbine Performance Prediction

Journal of Fluids Engineering ◽

10.1115/1.3242595 ◽

1986 ◽

Vol 108 (4) ◽

pp. 400-406 ◽

Cited By ~ 21

Author(s):

A. A. Afjeh ◽

T. G. Keith

Keyword(s):

Wind Turbine ◽

Performance Prediction ◽

Vortex Method ◽

Computational Effort ◽

Horizontal Axis ◽

Tip Vortex ◽

Performance Parameters ◽

Horizontal Axis Wind Turbine ◽

Turbine Performance ◽

Free Wake

Based on the assumption that wake geometry of a horizontal-axis wind turbine closely resembles that of a hovering helicopter, a method is presented for predicting the performance of a horizontal-axis wind turbine. A vortex method is used in which the wake is composed of an intense tip-vortex and a diffused inboard wake. Performance parameters are calculated by application of the Biot-Savart law along with the Kutta-Joukowski theorem. Predictions are shown to compare favorably with values from a more complicated full free wake analysis and with existing experimental data, but require more computational effort than an existing fast free wake method.

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Some effects of flow expansion on the aerodynamics of horizontal-axis wind turbines

10.5194/wes-2021-52 ◽

2021 ◽

Author(s):

David Wood ◽

Eric Limacher

Keyword(s):

Axial Velocity ◽

Momentum Equation ◽

Horizontal Axis ◽

Speed Ratio ◽

Axial Component ◽

Horizontal Axis Wind Turbine ◽

Tip Vortices ◽

Tip Speed Ratio ◽

Constant Pitch ◽

Far Wake

Abstract. Upwind of an energy-extracting horizontal-axis wind turbine, the flow expands as it approaches the rotor, and the expansion continues in the vorticity-bearing wake behind the rotor. The upwind expansion has long been known to influence the axial momentum equation through the axial component of the pressure, although the extent of the influence has not been quantified. Starting with the impulse analysis of Limacher & Wood (2020), but making no further use of impulse techniques, we demonstrate that the expansion redistributes momentum from the external flow to the wake and derive its exact expression when the rotor is circumferentially uniform. This expression, which depends on the radial velocity and the axial induction factor, is added to the thrust equation containing the pressure on the back of the disk. Removing the pressure to obtain a practically useful equation shows the axial induction in the far-wake is twice the value at the rotor only at high tip speed ratio and only if the relationship between vortex pitch and axial induction in non-expanding flow carries over to the expanding case. At high tip speed ratio, we assume that the expanding wake approaches the "Joukowsky'' model of a hub vortex on the axis of rotation and tip vortices originating from each blade. The additional assumption that the helical tip vortices have constant pitch, allows a semi-analytic treatment of their effect on the rotor flow. Expansion modifies the relation between the pitch and induced axial velocity so that the far-wake area and induction are significantly less than twice the values at the rotor. There is a moderate decrease – about 6 % – in the power production and a similar size error occurs in the familiar axial momentum equation involving the axial velocity.

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PENGARUH JUMLAH BLADE DAN VARIASI PANJANG CHORD TERHADAP PERFORMANSI TURBIN ANGIN SUMBU HORIZONTAL (TASH)

Dinamika Teknik Mesin ◽

10.29303/d.v4i2.60 ◽

2014 ◽

Vol 4 (2) ◽

Author(s):

I Kade Wiratama ◽

Made Mara ◽

L. Edsona Furqan Prina

Keyword(s):

Wind Turbine ◽

Energy Use ◽

Electrical Energy ◽

Vertical Axis ◽

Energy System ◽

Horizontal Axis ◽

Power Coefficient ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Horizontal Axis Wind Turbine

The willingness of electrical energy is one energy system has a very important role in the economic development of a country's survival. As one energy source (wind) can be converted into electrical energy with the use of a horizontal axis wind turbine. Wind Energy Conversion Systems (WECS) that we know are two wind turbines in general, ie the horizontal axis wind turbine and vertical axis wind turbine is one type of renewable energy use wind as an energy generator. The purpose of this study was to determine the effect of the number of blade and the radius chord of rotation (n), Torque (T), Turbine Power (P), Power Coefficient (CP) and Tip Speed Ratio (λ) generated by the horizontal axis wind turbine with form linear taper. The results show that by at the maximum radius of the chord R3 the number blade 4 is at rotation = 302.700 rpm, Pturbine = 7.765 watt, Torque = 0.245 Nm, λ = 3.168 and Cp = 0.403 or 40.3%.

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