scholarly journals On the Performance of Small-Scale Horizontal Axis Tidal Current Turbines. Part 1: One Single Turbine

2020 ◽  
Vol 12 (15) ◽  
pp. 5985 ◽  
Author(s):  
Ramin Alipour ◽  
Roozbeh Alipour ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů ◽  
Seyed Alireza Ghazanfari
Keyword(s):  
Tidal Current ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Small Scale ◽  
Ansys Fluent ◽  
Thrust Coefficient ◽  
Tidal Current Energy ◽  
Tip Speed Ratio ◽  
Blade Number ◽  
Stability Performance

The blade number of a current tidal turbine is one of the essential parameters to increase the stability, performance and efficiency for converting tidal current energy into rotational energy to generate electricity. This research attempts to investigate the effect of blade number on the performance of a small-scale horizontal tidal current turbine in the case of torque, thrust coefficient and power coefficient. Towards this end and according to the blade element momentum theory, three different turbines, i.e., two, three and four-bladed, were modeled using Solidworks software based on S-814 airfoil and then exported to the ANSYS-FLUENT for computational flow dynamics (CFD) analysis. SST-K-ω turbulence model was used to predict the turbulence behavior and several simulations were conducted at 2 ≤ tip speed ratio ≤ 7. Pressure contours, turbulence kinetic energy contours, cut-in-speed-curves, and streamlines around the blades and rotors were extracted and compared to provide an ability for a deep discussion on the turbine performance. The results show that in the case of obtainable power, the optimal value of tip speed ratio is around 5, so that the maximum power was achieved for the four-bladed turbine. Out of optimal condition, higher blade number and lower blade number turbines should be used at less than and greater than the optimal values of tip speed ratio, respectively. The results of simulations for the three-bladed turbine were validated against the experimental data with good agreement.

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

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.

scholarly journals Studi Numerik: Pengaruh Omni-Directional Guide Vane (ODGV) Terhadap Efisiensi Turbin Angin Savonius Konvensional

2020 ◽  
Vol 15 (2) ◽  
pp. 82
Author(s):  
Yoga Arob Wicaksono
Keyword(s):  
Guide Vane ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Ansys Fluent ◽  
Tip Speed Ratio ◽  
S Parameter ◽  
Torque Coefficient

<p>Penelitian ini menyajikan analisa numerik pengaruh <em>Omni-Direction Guide Vane</em> (ODGV) terhadap efisiensi turbin angin Savonius konvensional. Tujuan utama dari penelitian ini adalah untuk mengembangkan desain ODGV yang dapat meningkatkan efisiensi turbin angin Savonius skala kecil. Tiga desain ODGV dengan sudut kemiringan 50<sup>o</sup>, 60<sup>o</sup>, dan 70<sup>o</sup> dianalisa menggunakan<em> </em>software ANSYS-Fluent R15<em>. </em>Simulasi dilakukan pada model 2D dengan model turbulen <em>k-ε</em> standar dan kecepatan angin konstan 6 m/s. Parameter efisiensi yang dihitung pada simulasi ini antara lain: <em>torque coefficient</em><em> </em>(<em>C</em><sub>t</sub>)<em>, power coefficient</em><em> </em>(<em>C</em><sub>p</sub>)<em>, </em>dan <em>tip speed ratio</em> (TSR). Hasil penelitian menunjukkan bahwa OGDV mampu meningkatkan efisiensi turbin angin Savonius sebesar 82%. Peningkatan tertinggi dicapai dengan menggunakan variasi ODGV dengan sudut kemiringan 50<sup>o</sup>.</p>

Aerodynamic Design and Wind Tunnel Tests of Small-scale Horizontal-axis Wind Turbines for Low Tip Speed Ratio Applications

2022 ◽  
pp. 1-34
Author(s):  
Ojing Siram ◽  
Neha Kesharwani ◽  
Niranjan Sahoo ◽  
Ujjwal K. Saha
Keyword(s):  
Wind Tunnel ◽  
Wind Turbines ◽  
Pitch Angle ◽  
Horizontal Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Small Scale ◽  
Wind Tunnel Tests ◽  
Tip Speed Ratio ◽  
Horizontal Axis Wind Turbines

Abstract In recent times, the application of small-scale horizontal axis wind turbines (SHAWTs) has drawn interest in certain areas where the energy demand is minimal. These turbines, operating mostly at low Reynolds number (Re) and low tip speed ratio (λ) applications, can be used as stand-alone systems. The present study aims at the design, development, and testing of a series of SHAWT models. On the basis of aerodynamic characteristics, four SHAWT models viz., M1, M2, M3, and M4 composed of E216, SG6043, NACA63415, and NACA0012 airfoils, respectively have been developed. Initially, the rotors are designed through blade element momentum theory (BEMT), and their power coefficient have been evaluated. Thence, the developed rotors are tested in a low-speed wind tunnel to find their rotational frequency, power and power coefficient at design and off-design conditions. From BEMT analysis, M1 shows a maximum power coefficient (Cpmax) of 0.37 at λ = 2.5. The subsequent wind tunnel tests on M1, M2, M3, and M4 at 9 m/s show the Cpmax values to be 0.34, 0.30, 0.28, and 0.156, respectively. Thus, from the experiments, the M1 rotor is found to be favourable than the other three rotors, and its Cpmax value is found to be about 92% of BEMT prediction. Further, the effect of pitch angle (θp) on Cp of the model rotors is also examined, where M1 is found to produce a satisfactory performance within ±5° from the design pitch angle (θp, design).

scholarly journals Drag coefficient calculation of modified Myring-Savonius wind turbine with numerical simulations

2020 ◽  
Vol 10 (2) ◽  
pp. 73-84
Author(s):  
Mahmoud Saleh ◽  
Endre Kovács
Keyword(s):  
Drag Coefficient ◽  
Wind Turbine ◽  
Primary Objective ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Energy Potential ◽  
Cross Sectional ◽  
Ansys Fluent ◽  
Tip Speed Ratio ◽  
Savonius Wind Turbine

Nowadays the importance of renewable energy is growing, and the utilization of the low wind energy potential is getting crucial. There are turbines with low and high tip speed ratio. Turbines with low tip speed ratio such as the Savonius wind turbine can generate adequate amount of torque at low wind velocities. These types of turbines are also called drag machines. The geometry of the blade can greatly influence the efficiency of the device. With Computational Fluid Dynamics (CFD) method, several optimizations can be done before the production. In our paper the Savonius wind turbine blade geometry was designed based on the so-called Myring equation. The primary objective of this paper was to investigate the drag coefficient of the force acting on the surface of the blade. Also, the Karman vortex was investigated and the space ratio of that vortex in our simulation was compared to a typical one. The power coefficient of a new Savonius turbine was investigated at different values of top speed ratio (TSR). For the sake of simplicity, a 2D cross-sectional area was investigated in the simulation with ANSYS Fluent 19.2.

Large Eddy Simulations of Ventilated Micro Hydrokinetic Turbine

2017 ◽  
Author(s):  
Cosan Daskiran ◽  
Bashar Attiya ◽  
I-Han Liu ◽  
Jacob Riglin ◽  
Alparslan Oztekin
Keyword(s):  
Axial Direction ◽  
Large Eddy Simulations ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Multiphase Model ◽  
Thrust Coefficient ◽  
Tip Speed Ratio ◽  
Hydrokinetic Turbine ◽  
Large Eddy ◽  
Aeration Process

Large eddy simulations of pre-designed micro-hydrokinetic turbine were conducted to investigate the oxygen transfer from air to water. Simulations were performed in extreme conditions having a tip-speed ratio of 3.8 that is higher than the tip-speed ratio at turbine’s design point. Air was injected from the turbine hub downstream in axial direction. Both single phase and multiphase simulations were performed to reveal the influence of air admission on the flow structures and the turbine performance. The mixture multiphase model was employed in multiphase simulation. The results indicated that turbine power generation was reduced roughly 10.5% by air admission, however the torque applied on turbine surface in axial direction did not vary significantly by aeration. The aeration assisted in the suppression of vortices within the flow field. The deviation of the power coefficient and the thrust coefficient was reduced roughly 32% through the inclusion of aeration process.

Design & optimization of a small wind turbine blade for operation at low wind speed

2015 ◽  
Vol 12 (1) ◽  
pp. 83-94 ◽  
Author(s):  
Manoj Kumar Chaudhary ◽  
Anindita Roy
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Twist Angle ◽  
Chord Length ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Design Point ◽  
Tip Speed Ratio ◽  
Blade Number ◽  
Selection Of

A small wind turbine blade was designed and optimized in this research paper. The blade plays an important role, because it is the most important part of the energy absorption system. Consequently, the blade has to be designed carefully to enable to absorb energy with its greatest efficiency. The main objective of this paper is to optimized blade number and selection of tip speed ratio corresponding to the solidity. The power performance of small horizontal axis wind turbines was simulated in detail using blade element momentum methods (BEM). In this paper for wind blade design various factors such as tip loss, hub loss, drag coefficient, and wake were considered. The design process includes the selection of the wind turbine type and the determination of the blade airfoil, twist angle distribution along the radius, and chord length distribution along the radius. A parametric study that will determine if the optimized values of blade twist angle and chord length create the most efficient blade geometry. The 3-bladed, 5-bladed and 7-bladed rotor achieved maximum values of Cp 0.46, 0.5 and 0.48 at the tip speed ratio 7, 5 and 4 respectively. It was observed that using BEM theory, maximum Cp varied with strongly solidity and weakly with the blade number. The studies showed that the power coefficient increases upto blade number B = 5, while the blade number if increased above 5 then the power coefficient decreases at operating pitch angle equal to 3°. Highest Cp would have solidity between 4% to 6% for number of blade 3 and design point tip speed ratio of about "7". Highest Cp would have solidity ranging from 5% to 10% for number of blade 5 and 7 and design point tip speed ratio of about 5 and 4 respectively.

scholarly journals Performance assessment and optimization of a helical Savonius wind turbine by modifying the Bach’s section

2021 ◽  
Vol 3 (8) ◽  
Author(s):  
M. Niyat Zadeh ◽  
M. Pourfallah ◽  
S. Safari Sabet ◽  
M. Gholinia ◽  
S. Mouloodi ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Performance Assessment ◽  
Turbulent Flows ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Basic Model ◽  
Turbine Performance ◽  
Primary Model ◽  
Savonius Wind Turbine

AbstractIn this paper, we attempted to measure the effect of Bach’s section, which presents a high-power coefficient in the standard Savonius model, on the performance of the helical Savonius wind turbine, by observing the parameters affecting turbine performance. Assessment methods based on the tip speed ratio, torque variation, flow field characterizations, and the power coefficient are performed. The present issue was stimulated using the turbulence model SST (k- ω) at 6, 8, and 10 m/s wind flow velocities via COMSOL software. Numerical simulation was validated employing previous articles. Outputs demonstrate that Bach-primary and Bach-developed wind turbine models have less flow separation at the spoke-end than the simple helical Savonius model, ultimately improving wind turbines’ total performance and reducing spoke-dynamic loads. Compared with the basic model, the Bach-developed model shows an 18.3% performance improvement in the maximum power coefficient. Bach’s primary model also offers a 12.4% increase in power production than the initial model’s best performance. Furthermore, the results indicate that changing the geometric parameters of the Bach model at high velocities (in turbulent flows) does not significantly affect improving performance.

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

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.

Performance study of twisted Darrieus hydrokinetic turbine with novel blade design

2021 ◽  
pp. 1-37
Author(s):  
Mabrouk Mosbahi ◽  
Mouna Derbel ◽  
Mariem Lajnef ◽  
Bouzid Mosbahi ◽  
Zied Driss ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Maximum Power ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Small Scale ◽  
Performance Study ◽  
Hydrokinetic Turbine ◽  
Blade Shape ◽  
Water Turbine ◽  
Water Canals

Abstract Twisted Darrieus water turbine is receiving growing attentiveness for small-scale hydropower generation. Accordingly, the need for raised water energy conversion incentivizes researchers to focalise on the blade shape optimization of twisted Darrieus turbine. In view of this, an experimental analysis has been performed to appraise the efficiency of a spiral Darrieus water rotor in the present work. To better the performance parameters of the studied water rotor with twisted blades, three novel blade shapes, namely U-shaped blade, V-shaped blade and W-shaped blade, have been numerically tested using a computational fluid dynamics three-dimensional numerical model. Maximum power coefficient of Darrieus rotor reaches 0.17 at 0.63 tip-speed ratio using twisted blades. Using V-shaped blades, maximum power coefficient has been risen up to 0.185. The current study could be practically applied to provide more effective employment of twisted Darrieus turbines and to improve the generated power from flowing water such as river streams, tidal currents, or other man made water canals.

Arriving at the Optimum Overlap Ratio for an Elliptical-Bladed Savonius Rotor

2017 ◽  
Author(s):  
Nur Alom ◽  
Ujjwal K. Saha
Keyword(s):  
Numerical Study ◽  
Superior Performance ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Small Scale ◽  
Efficient Manner ◽  
Ansys Fluent ◽  
Savonius Rotor ◽  
Velocity Magnitude ◽  
Overlap Ratio

The Savonius rotor appears to be particularly promising for the small-scale applications because of its design simplicity, good starting ability, and insensitivity to wind directions. There has been a growing interest in recent times to harness wind energy in an efficient manner by developing newer blade profiles of Savonius rotor. The overlap ratio (OR), one of the important geometric parameters, plays a crucial role in the turbine performance. In a recent study, an elliptical blade profile with a sectional cut angle (θ) of 47.5° has demonstrated its superior performance when set at an OR = 0.20. However, this value of OR is ideal for a semicircular profile, and therefore, requires further investigation to arrive at the optimum overlap ratio for the elliptical profile. In view of this, the present study attempts to make a systemic numerical study to arrive at the optimum OR of the elliptical profile having sectional cut angle, θ = 47.5°. The 2D unsteady simulation is carried out around the elliptical profile considering various overlap ratios in the range of 0.0 to 0.30. The continuity, unsteady Reynolds Averaged Navier-Stokes (URANS) equations and two equation eddy viscosity SST (Shear Stress transport) k-ω model are solved by using the commercial finite volume method (FVM) based solver ANSYS Fluent. The torque and power coefficients are calculated as a function of tip speed ratio (TSR) and at rotating conditions. The total pressure, velocity magnitude and turbulence intensity contours are obtained and analyzed to arrive at the intended objective. The numerical simulation demonstrates an improved performance of the elliptical profile at an OR = 0.15.

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