Numerical Investigation on the Effects of Airfoil Leading Edge Radius on the Aerodynamic Performance of H-Rotor Darrieus Vertical Axis Wind Turbine

This paper numerically investigates the effects of airfoil leading edge radius on the aerodynamic characteristics of H-rotor Darrieus vertical axis wind turbine (VAWT). 10 modified airfoils are generated by changing the leading edge radius of the base NACA 0015 airfoil from 1%c to 9%c, respectively. A 2D unsteady Computational Fluid Dynamics (CFD) model is established and validated with the previously published experimental data. The power, torque, and flow field characteristics of the rotors are analyzed. The results indicate that the maximum and minimum power coefficient at the optimum tip speed ratio (TSR) are obtained for the LE-5%c and LE-1%c model, respectively. The best aerodynamic characteristics are determined by the LE-5%c model below the optimum TSR and the LE-3%c model beyond the optimum TSR. The torque characteristics and pressure distribution for the single blades with different airfoil leading edge radius show an obvious difference in the upwind region and a very small difference in the downwind region. Moreover, the airfoil leading edge radius influences the strength, region, and diffusion rate of the vortices, being the main reason for the observed differences in instantaneous torque coefficient and power coefficient. The vortices of the LE-1%c model are stronger, larger, and diffuse slower than those of the LE-2%c and LE-5%c model at the optimum TSR.

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Numerical Research on the Characteristics of Lift-Drag Type Vertical Axis Wind Turbine

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.189.448 ◽

2012 ◽

Vol 189 ◽

pp. 448-452

Author(s):

Yan Jun Chen ◽

Guo Qing Wu ◽

Yang Cao ◽

Dian Gui Huang ◽

Qin Wang ◽

...

Keyword(s):

Wind Turbine ◽

Vertical Axis ◽

Chord Length ◽

Power Coefficient ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Tip Speed Ratio ◽

Middle Range ◽

Parabolic Form ◽

Cfd Method

Numerical studies are conducted to research the performance of a kind of lift-drag type vertical axis wind turbine (VAWT) affected by solidity with the CFD method. Moving mesh technique is used to construct the model. The Spalart-Allmaras one equation turbulent model and the implicit coupled algorithm based on pressure are selected to solve the transient equations. In this research, how the tip speed ratio and the solidity of blade affect the power coefficient (Cp) of the small H-VAWT is analyzed. The results indicate that Cp curves exhibit approximate parabolic form with its maximum in the middle range of tip speed ratio. The two-blade wind turbine has the lowest Cp while the three-blade one is more powerful and the four-blade one brings the highest power. With the certain number of blades, there is a best chord length, and too long or too short chord length may reduce the Cp.

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Experimental Study of Vertical Axis Wind Turbine with Wind Speed Self-Adapting

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.215-216.1323 ◽

2012 ◽

Vol 215-216 ◽

pp. 1323-1326

Author(s):

Ming Wei Xu ◽

Jian Jun Qu ◽

Han Zhang

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Wind Velocity ◽

Vertical Axis ◽

Maximum Power ◽

The Self ◽

Power Coefficient ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Opening And Closing

A small vertical axis wind turbine with wind speed self-adapting was designed. The diameter and height of the turbine were both 0.7m. It featured that the blades were composed of movable and fixed blades, and the opening and closing of the movable blades realized the wind speed self-adapting. Aerodynamic performance of this new kind turbine was tested in a simple wind tunnel. Then the self-starting and power coefficient of the turbine were studied. The turbine with load could reliably self-start and operate stably even when the wind velocity was only 3.6 m/s. When the wind velocity was 8 m/s and the load torque was 0.1Nm, the movable blades no longer opened and the wind turbine realized the conversion from drag mode to lift mode. With the increase of wind speed, the maximum power coefficient of the turbine also improves gradually. Under 8 m/s wind speed, the maximum power coefficient of the turbine reaches to 12.26%. The experimental results showed that the new turbine not only improved the self-starting ability of the lift-style turbine, but also had a higher power coefficient in low tip speed ratio.

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A Dynamic Rotor Vertical-Axis Wind Turbine with a Blade Transitioning Capability

Energies ◽

10.3390/en12081446 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1446 ◽

Cited By ~ 2

Author(s):

Elie Antar ◽

Amne El Cheikh ◽

Michel Elkhoury

Keyword(s):

Wind Turbine ◽

Average Power ◽

Vertical Axis ◽

Power Coefficient ◽

Speed Ratio ◽

Optimized Design ◽

Detached Eddy Simulation ◽

Vertical Axis Wind Turbine ◽

Eddy Simulation ◽

Delayed Detached Eddy Simulation

This work presents an optimized design of a dynamic rotor vertical-axis wind turbine (DR VAWT) which maximizes the operational tip-speed ratio (TSR) range and the average power coefficient (Cp) value while maintaining a low cut-in wind velocity. The DR VAWT is capable of mimicking a Savonius rotor during the start-up phase and transitioning into a Darrieus one with increasing rotor radius at higher TSRs. The design exploits the fact that with increasing rotor radius, the TSR value increases, where the peak power coefficient is attained. A 2.5D improved delayed detached eddy simulation (IDDES) approach was adopted in order to optimize the dynamic rotor design, where results showed that the generated blades’ trajectories can be readily replicated by simple mechanisms in reality. A thorough sensitivity analysis was conducted on the generated optimized blades’ trajectories, where results showed that they were insensitive to values of the Reynolds number. The performance of the DR VAWT turbine with its blades following different trajectories was contrasted with the optimized turbine, where the influence of the blade pitch angle was highlighted. Moreover, a cross comparison between the performance of the proposed design and that of the hybrid Savonius–Darrieus one found in the literature was carefully made. Finally, the effect of airfoil thickness on the performance of the optimized DR VAWT was thoroughly analyzed.

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Application of Variable Blade Pitch Control on Improving the Performance of Vertical Axis Wind Turbine

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.229-231.2339 ◽

2012 ◽

Vol 229-231 ◽

pp. 2339-2342

Author(s):

J.C. Cheng ◽

S.J Su ◽

J.J Miau

Keyword(s):

Wind Turbine ◽

Vertical Axis ◽

Aerodynamic Characteristics ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Energy Capture ◽

Pitch Control ◽

Tip Speed Ratio ◽

Torque Coefficient ◽

Variable Pitch Control

A three blades vertical axis wind turbine simulation is performed to study the unsteady aerodynamic characteristics with blade pitch control. Several fixed and variable blade pitch models under different tip speed ratio are adopted to improve performance of the wind turbine. Results show that an appropriate pitch control model can effectively decrease the range of negative torque regime to reduce the vibration of the wind turbine. Besides, the average torque coefficient as well as the energy capture efficiency can be also improved, especially for the lower tip speed ratio. The overall efficiency of the wind turbines in power generation will be enhanced. For the cases under the tip speed ratio between 1 and 3, the efficiency can be enhanced 243% and 486% for fixed and variable pitch control models respectively as comparing with non-pitch control cases.

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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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Performance Improvements for a Vertical Axis Wind Turbine by Means of Gurney Flap

Journal of Fluids Engineering ◽

10.1115/1.4044995 ◽

2019 ◽

Vol 142 (2) ◽

Cited By ~ 2

Author(s):

Yan Yan ◽

Eldad Avital ◽

John Williams ◽

Jiahuan Cui

Keyword(s):

Wind Turbine ◽

Stokes Equations ◽

Numerical Study ◽

Vertical Axis ◽

Power Coefficient ◽

Navier Stokes ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Performance Improvements ◽

Gurney Flap

Abstract A numerical study was carried out to investigate the effects of a Gurney flap (GF) on the aerodynamics performance of the NACA 00 aerofoil and an associated three-blade rotor of a H-type Darrieus wind turbine. The flow fields around a single aerofoil and the vertical axis wind turbine (VAWT) rotor are studied using unsteady Reynolds-averaged Navier–Stokes equations (URANS). The height of GF ranges from 1% to 5% of the aerofoil chord length. The results show that the GF can increase the lift and lift-to-drag ratio of the aerofoil as associated with the generation of additional vortices near the aerofoil trailing edge. As a result, adding a GF can significantly improve the power coefficient of the VAWT at low tip speed ratio (TSR), where it typically gives low power production. The causing mechanism is discussed in detail, pointing to flow separation and dynamic stall delay.

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Blade Offset and Pitch Effects on a High Solidity Vertical Axis Wind Turbine

Wind Engineering ◽

10.1260/030952409789140955 ◽

2009 ◽

Vol 33 (3) ◽

pp. 237-246 ◽

Cited By ~ 62

Author(s):

Andrzej J. Fiedler ◽

Stephen Tullis

Keyword(s):

Wind Speed ◽

Wind Tunnel ◽

Wind Turbine ◽

Leading Edge ◽

Vertical Axis ◽

Small Scale ◽

Vertical Axis Wind Turbine ◽

Data Set ◽

Naca 0015 ◽

Base Data

A high solidity, small scale, 2.5m diameter by 3m high Vertical Axis Wind Turbine (VAWT) consisting of three NACA 0015 profile blades, each with a span of 3m and a chord length of 0.4m, was tested in an open-air wind tunnel facility to investigate the effects of preset toe-in and toe-out turbine blade pitch. The effect of blade mount-point offset was also investigated. The results from these tests are presented for a range of tip speed ratios, and compared with an extensive base data set obtained for a nominal wind speed of 10m/s. Results show measured performance decreases of up to 47% for toe-in, and increases of up to 29% for toe-out blade pitch angles, relative to the zero preset pitch case. Also, blade mount-point offset tests indicate decreases in performance as the mount location is moved from mid-chord towards the leading edge, as a result of an inherent toe-in condition. Observations indicate that these performance decreases may be minimized by compensating for the blade mount offset with a toe-out preset pitch. The trends of the preset blade pitch tests agree with those found in literature for much lower solidity turbines.

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Power Enhancement of a Vertical Axis Wind Turbine Equipped with an Improved Duct

Energies ◽

10.3390/en14185780 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5780

Author(s):

Mohammad Hassan Ranjbar ◽

Behnam Rafiei ◽

Seyyed Abolfazl Nasrazadani ◽

Kobra Gharali ◽

Madjid Soltani ◽

...

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Flow Characteristics ◽

Maximum Velocity ◽

Leading Edge ◽

Vertical Axis ◽

Power Coefficient ◽

Vertical Axis Wind Turbine ◽

Numerical Solver ◽

Main Components

Efforts to increase the power output of wind turbines include Diffuser Augmented Wind Turbines (DAWT) or a shroud for the rotor of a wind turbine. The selected duct has three main components: a nozzle, a diffuser, and a flange. The combined effect of these components results in enriched upstream velocity for the rotor installed in the throat of the duct. To obtain the maximum velocity in the throat of the duct, the optimum angles of the three parts have been analyzed. A code was developed to allow all the numerical steps including changing the geometries, generating the meshes, and setting up the numerical solver simultaneously. Finally, the optimum geometry of the duct has been established that allows a doubling of the flow velocity. The flow characteristics inside the duct have also been analyzed in detail. An H-Darrieus Vertical Axis Wind Turbine (VAWT) has been simulated inside the optimized duct. The results show that the power coefficient of the DAWT can be enhanced up to 2.9 times. Deep dynamic stall phenomena are captured perfectly. The duct advances the leading-edge vortex generation and delays the vortex separation.

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Studi simulasi penggunaan airfoil naca 6412 sebagai sudu pada turbin angin crossflow melalui pemodelan CFD 2 dimensi

Jurnal Teknik Mesin Indonesia ◽

10.36289/jtmi.v13i1.87 ◽

2018 ◽

Vol 13 (1) ◽

pp. 28

Author(s):

Muhammad Ivan Fadhil Hendrawan ◽

Dominicus Danardono ◽

Syamsul Hadi

Keyword(s):

Wind Turbine ◽

Constant Velocity ◽

Cross Flow ◽

Vertical Axis ◽

Power Coefficient ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Ansys Fluent ◽

Tip Speed Ratio ◽

Blade Number

AbstractThe simulation aimed to understand the effect of the angle of blade number and blade number of vertical axis wind turbine with cross flow runner to enhance the performance of wind turbine. The turbine had 20, 22, and 24 number of blades. Simulation was done in 2D analysis using ANSYS-Fluent. Tip speed ratio was varied in range of 0,1-0,5 with constant velocity inlet 2 m/s. The effect of blade numbers to torque and power coefficient were analyzed and compared. It had been found that the best power coefficient were 0,5 at tip speed ratio 0,3.

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Studi Eksperimen Pengaruh Jumlah Sudu Terhadap Kinerja Wind Turbine Crossflow

Jurnal Rekayasa Mesin ◽

10.32497/jrm.v16i2.2555 ◽

2021 ◽

Vol 16 (2) ◽

pp. 218

Author(s):

Fahrudin Fahrudin ◽

Fitri Wahyuni ◽

Dini Oktavitasari

Keyword(s):

Wind Turbine ◽

Alternative Energy ◽

Wind Tunnel Test ◽

Vertical Axis ◽

Power Coefficient ◽

Speed Ratio ◽

Test Scheme ◽

Vertical Axis Wind Turbine ◽

Tip Speed Ratio ◽

Torque Coefficient

Wind is an alternative energy that is environmentally friendly and sustainable. Therefore, we need a type of wind turbine that can receive wind from all directions. The crossflow type vertical axis wind turbine has a high torque coefficient at a low tip speed ratio. The purpose of this study was to determine the effect of the number of blades on the performance of the vertical axis crossflow wind turbine. The experimental test was carried out by varying the number of blades. The configuration is analyzed using the experimental wind tunnel test scheme which has been modified in the section test section. The results showed that the number of blades 16 has a power coefficient ( ) = 0.23 tip speed ratio (TSR) = 0.42 at a wind speed of 4 m / s.

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