scholarly journals A Study on Diffuser Augmentation of a Tidal Turbine

2021 ◽  
Vol 83 (1) ◽  
pp. 170-177
Author(s):  
Evi Elisa Ambarita ◽  
Harinaldi ◽  
Nasruddin ◽  
Ridho Irwansyah
Keyword(s):  
Tidal Current ◽  
Fluid Dynamic ◽  
Tidal Energy ◽  
Power Coefficient ◽  
Optimized Design ◽  
Inflow Velocity ◽  
Cavitation Inception ◽  
Turbine Performance ◽  
Tidal Turbine ◽  
Turbine Design

As tidal energy is progressively earning attention worldwide, there is a lot of existing research about the tidal current potency and the tidal turbine design. Especially on turbine design, existing studies deduced that a diffuser augmentation is a superior choice to increase the turbine performance. However, the research in finding the best diffuser angle whose efficiency is maximum, yet minim cavity risk is still limited. Therefore, this study proposes an innovative, optimized design method on diffuser augmentation of a tidal turbine by comparing four diffuser angles in three inflow velocity circumstances. In particular, three airfoil blades design with a rotor diameter of 0.3 m was developed. The combination of computational fluid dynamic and multi-objective optimization using a general algorithm coupled with the artificial neural network was applied by considering the turbine’s power coefficient and cavitation inception as a trade-off objective. The numerical results display that the different inflow velocity affects the turbine performance insignificantly. The optimization analysis and comparison among four diffuser angles in three variations of inflow velocity show that the tidal turbine's optimal design with diffuser augmentation could be applied to all tidal current speed.

scholarly journals MaRINET2 Tidal Energy Round Robin Tests—Performance Comparison of a Horizontal Axis Turbine Subjected to Combined Wave and Current Conditions

2020 ◽  
Vol 8 (6) ◽  
pp. 463
Author(s):  
Benoît Gaurier ◽  
Stephanie Ordonez-Sanchez ◽  
Jean-Valéry Facq ◽  
Grégory Germain ◽  
Cameron Johnstone ◽  
...  
Keyword(s):  
Average Power ◽  
Flow Characteristics ◽  
Tidal Energy ◽  
Round Robin ◽  
Performance Comparison ◽  
Power Coefficient ◽  
Experimental Conditions ◽  
Simultaneous Generation ◽  
Turbine Performance ◽  
Tidal Turbine

This Round Robin Test program aims to establish the influence of the combined wave and current effect on the power capture and performance of a generic tidal turbine prototype. Three facilities offering similar range of experimental conditions have been selected on the basis that their dimensions along with the rotor diameter of the turbine translate into low blockage ratio conditions. The performance of the turbine shows differences between the facilities up to 25% in terms of average power coefficient, depending on the wave and current cases. To prevent the flow velocity increasing these differences, the turbine performance coefficients have been systematically normalized using a time-average disc-integrated velocity, accounting for vertical gradients over the turbine swept area. Differences linked to blockage effects and turbulence characteristics between facilities are both responsible for 5 to 10% of the power coefficient gaps. The intrinsic differences between the tanks play a significant role as well. A first attempt is given to show how the wave-current interaction effects can be responsible for differences in the turbine performance. In these tanks, the simultaneous generation of wave and current is a key part often producing disruptions in both of these flow characteristics.

Inflow Measurement in a Tidal Strait for Deploying Tidal Current Turbines: Lessons, Opportunities and Challenges

2010 ◽  
Author(s):  
Ye Li ◽  
Jonathan A. Colby ◽  
Neil Kelley ◽  
Robert Thresher ◽  
Bonnie Jonkman ◽  
...  
Keyword(s):  
Tidal Current ◽  
Laboratory Tests ◽  
Critical Factor ◽  
Tidal Energy ◽  
Background Information ◽  
Commercial Development ◽  
Mean Velocity ◽  
Topic Area ◽  
East River ◽  
Turbine Performance

Tidal energy has received increasing attention over the past decade. This increasing focus on capturing the energy from tidal currents has brought about the development of many designs for tidal current turbines. Several of these turbines are progressing rapidly from design to prototype and pre-commercial stages. As these systems near commercial development, it becomes increasingly important that their performance be validated through laboratory tests (e.g., towing tank tests) and sea tests. Several different turbine configurations have been tested recently. The test results show significant differences in turbine performance between laboratory tests, numerical simulations, and sea tests. Although the mean velocity of the current is highly predictable, evidence suggests a critical factor in these differences is the unsteady inflow. To understand the physics and the effect of the inflow on turbine performance and reliability, Verdant Power (Verdant) and the National Renewable Energy Laboratory (NREL) have engaged in a partnership to address the engineering challenges facing marine current turbines. As part of this effort, Verdant deployed Acoustic Doppler Current Profiler (ADCP) equipment to collect data from a kinetic hydropower system (KHPS) installation at the Roosevelt Island Tidal Energy (RITE) project in the East River in New York City. The ADCP collected data for a little more than one year, and this data is critical for properly defining the operating environment needed for marine systems. This paper summarizes the Verdant-NREL effort to study inflow data provided by the fixed, bottom-mounted ADCP instrumentation and how the data is processed using numerical tools. It briefly reviews previous marine turbine tests and inflow measurements, provides background information from the RITE project, and describes the test turbine design and instrumentation setup. This paper also provides an analysis of the measured time domain data and a detailed discussion of shear profiling, turbulence intensity, and time-dependent fluctuations of the inflow. The paper concludes with suggestions for future work. The analysis provided in this paper will benefit future turbine operation studies. In addition, this study, as well as future studies in this topic area, will be beneficial to environmental policy makers and fishing communities.

Computational fluid dynamic analysis of roof-mounted vertical-axis wind turbine with diffuser shroud, flange, and vanes

2018 ◽  
Vol 42 (4) ◽  
pp. 404-415
Author(s):  
H. Abu-Thuraia ◽  
C. Aygun ◽  
M. Paraschivoiu ◽  
M.A. Allard
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Guide Vane ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes ◽  
Turbine Design

Advances in wind power and tidal power have matured considerably to offer clean and sustainable energy alternatives. Nevertheless, distributed small-scale energy production from wind in urban areas has been disappointing because of very low efficiencies of the turbines. A novel wind turbine design — a seven-bladed Savonius vertical-axis wind turbine (VAWT) that is horizontally oriented inside a diffuser shroud and mounted on top of a building — has been shown to overcome the drawback of low efficiency. The objective this study was to analyze the performance of this novel wind turbine design for different wind directions and for different guide vanes placed at the entrance of the diffuser shroud. The flow field over the turbine and guide vanes was analyzed using computational fluid dynamics (CFD) on a 3D grid for multiple tip-speed ratios (TSRs). Four wind directions and three guide-vane angles were analyzed. The wind-direction analysis indicates that the power coefficient decreases to about half when the wind is oriented at 45° to the main axis of the turbine. The analysis of the guide vanes indicates a maximum power coefficient of 0.33 at a vane angle of 55°.

Exploring the Effect of Length and Angle on NACA 0010 for Diffuser Design in Tidal Current Turbines

2012 ◽  
Vol 201-202 ◽  
pp. 438-441 ◽  
Author(s):  
Nasir Mehmood ◽  
Liang Zhang ◽  
Jawad Khan
Keyword(s):  
Kinetic Energy ◽  
Tidal Current ◽  
Current Flow ◽  
Tidal Energy ◽  
Research Community ◽  
Financial Resources ◽  
Considerable Time ◽  
Tidal Turbines ◽  
Tidal Turbine

Tidal energy is one of the most predictable forms of renewable energy.Tides posses both potential and kinetic energy. Tidal energy can be utilized by capturing potential energy i.e. by means of tidal barrage and tidal fence or by capturing kinetic energy i.e. by menas of tidal current technologies. This study is focused on diffuser augmented tidal turbines that capture the kinetic energy. The power generated by a tidal turbine is directly proportional to the cube of velocity of current flow. The role of the diffuser in diffuser augmented tidal turbines is to help accelerate the incoming current velocity. Consequently, the efficiency of the turbine is significantly increasedby using adiffuser. The research community is investing considerable time and financial resources in thisgrowingdomain. The diffuser augmented tidal turbinesresearch datais rather scarce due to their emerging nature, large and costly research & development setup, startup cost and proprietary issues. The purpose of this paper is to study the effect of length and angle on NACA 0010airfoil for diffuser design. Numerical simulation is carried out to investigate velocity and mass flow rate at the throat. The drag force due to diffuser installation is also calculated.

A Study on Performance of New Tidal Energy Converter for Tidal Current Extraction Using Computational Fluid Dynamics

2016 ◽  
Author(s):  
Manh Hung Nguyen ◽  
Haechang Jeong ◽  
Changjo Yang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Tidal Current ◽  
Tidal Energy ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Energy Converter ◽  
Double Row ◽  
Tidal Turbines ◽  
Stage Of Development

Renewal energy technologies are increasingly popular to ensure future energy sustainability and to balance environmental issues. The growing interest in exploring tidal energy has compelling reasons such as security and diversity of supply, intermittent but predictable and limited social and environmental impacts. The energy available in tidal currents or other artificial water channels is being considered as viable source of renewable power. Hydrokinetic conversion systems, albeit mostly at its early stage of development, may appear suitable in harnessing energy from such renewable resources. A concept of tidal energy converter (TEC) which is based on shape of the conventional water wheels, is introduced in this study. Basically, this turbine has several special features that are potentially more advantageous than the conventional tidal turbines, such as propeller type tidal turbines. The research aims to study the possibility of twelve-blade turbine in extracting the hydrokinetic energy of tidal current and converting it into electricity, and evaluate the performance of the turbine at different given arrangements of blades (single and double rows) using Computational Fluid Dynamics (CFD). In all cases of tip-speed ratio (TSR), the twelve-blade double-row type obtains higher power efficiency, especially about 20% power coefficient at TSR = 0.75, in comparison with 13% power coefficient of the single-row one. Furthermore, by changing the arrangement of rotating blades, the torque’s absorption from the rotor shaft of twelve-blade double-row turbine is more uniform due to the less interrupted and fluctuated generation of force for a period of time (one revolution of the rotor).

Numerical Analysis of Tidal Turbine Performance for Floating Platform

2019 ◽  
Author(s):  
Xiuqing Xing ◽  
Chang Wei Kang ◽  
George Xu ◽  
Jing Lou ◽  
Ken Takagi ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Power Coefficient ◽  
Cfd Model ◽  
Floating Platform ◽  
Data Simulation ◽  
Turbine Performance ◽  
Tidal Turbine ◽  
Heading Angle ◽  
Simulation Results ◽  
A Current

Abstract A three dimensional Computational Fluid Dynamics (CFD) model solving Reynolds-averaged Navier-Stokes (RANS) equations with k-ε turbulence model has been developed based on OpenFoam to investigate a tidal turbine performance. The CFD model is validated by comparing the simulation results with the performance characteristic data. Simulation results match the measured data with discrepancies less than 5.4%. The well validated model is then adopted to predict the turbine performance with a current heading angle of 30 degree. The simulated turbine power coefficient and flow field details from OpenFoam are compared with those obtained from commercial software ANSYS FLUENT for verification. The two simulated results match each other with a difference of only 3%. Simulated results indicate that the turbine power output drops significantly when the tidal turbine operates with a current heading angle of 30 degree. The performance loss due to a misalignment between the current and the turbine axis is analyzed with the aim to identify main causes and provide recommendations to tidal turbine operation.

scholarly journals Effect of a Support Tower on the Performance and Wake of a Tidal Current Turbine

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1059
Author(s):  
Zia Ur Rehman ◽  
Saeed Badshah ◽  
Amer Farhan Rafique ◽  
Mujahid Badshah ◽  
Sakhi Jan ◽  
...  
Keyword(s):  
Tidal Current ◽  
Tidal Energy ◽  
Coefficient Of Performance ◽  
Speed Ratio ◽  
Cfd Simulations ◽  
Ansys Cfx ◽  
Tidal Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Tidal Current Turbine ◽  
Current Turbine

Tidal energy is one of the major sources of renewable energy. To accelerate the development of tidal energy, improved designs of Tidal Current Turbine (TCT) are necessary. The effect of tower on performance and wake of TCT is investigated using Computational Fluid Dynamics (CFD) simulations. Transient analysis with transient rotor stator frame change model and shear stress transport turbulence model are utilized in ANSYS CFX. An experimentally validated numerical model with full scale tidal turbine with a blockage ratio of 14.27% and Tip Speed Ratio (TSR) 4.87 is used to simulate the effect of different tower diameters on performance and wake. The effect of different tower diameters is quantified in terms of coefficient of performance (CP). Coefficient of performance for a 3.5 m tower diameter is 0.472 which is followed by 3, 2.5 and 2 m with coefficients of performance of 0.476, 0.478 and 0.476 respectively. Similarly, the coefficient of thrust (CT) on the rotor for 3.5 m tower diameter is 0.902, for 3 m diameter 0.906 and for 2.5 and 2 m diameters are 0.908 and 0.906 respectively.

scholarly journals Simulasi Performa Turbin Propeller Dengan Sudut Pitch Yang Divariasikan

2020 ◽  
Vol 6 (1) ◽  
pp. 54
Author(s):  
Pribadyo Pribadyo ◽  
Hadiyanto H ◽  
Jamari J
Keyword(s):  
Turbine Blade ◽  
Cfd Simulation ◽  
Power Coefficient ◽  
Design Parameters ◽  
Blade Angle ◽  
Runner Blade ◽  
Turbine Performance ◽  
Turbine Runner ◽  
Turbine Design ◽  
Blade Pitch Angle

 Propeller turbine performance can be improved by changing the turbine design parameters. One method that was developed is to vary the blade angle on the runner's blades. Analysis of the influence of blade angle on propeller turbine performance is done through numerical simulations based on computational fluid dynamics. The simulation is done with variations of propeller turbine blade angles of 180, 230, and 280 at flow rates of 0.08 m/s to 0.5 m/s. Simulation results show turbines with 250 blade angles have the best performance compared to turbine blade angles of 230 and 280. While the turbine blade angles of 230 tend to have higher performance compared to angles of 280 even though both have peak values for the corresponding power coefficient. Keywords—Propeller turbine, runner blade, pitch angle, CFD simulation

scholarly journals Designing multi-rotor tidal turbine fences

2018 ◽  
Vol 1 (1 (Aug)) ◽  
pp. 61-70 ◽  
Author(s):  
C. R. Vogel ◽  
R. H. J. Willden
Keyword(s):  
Navier Stokes ◽  
Disk Model ◽  
Local Flow ◽  
Cavitation Inception ◽  
Tidal Turbines ◽  
Solidity Ratio ◽  
Flow Phenomena ◽  
Tidal Turbine ◽  
Turbine Design ◽  
Confined Flows

An embedded Reynolds-Averaged Navier-Stokes blade element actuator disk model is used to investigate the hydrodynamic design of tidal turbines and their performance in a closely spaced cross-stream fence. Turbines designed for confined flows are found to require a larger blade solidity ratio than current turbine design practices imply in order to maximise power. Generally, maximum power can be increased by operating turbines in more confined flows than they were designed for, although this also requires the turbines to operate at a higher rotational speed, which may increase the likelihood of cavitation inception. In-array turbine performance differs from that predicted from single turbine analyses, with cross-fence variation in power and thrust developing between the inboard and outboard turbines. As turbine thrust increases the cross-fence variation increases, as the interference effects between adjacent turbines strengthen as turbine thrust increases, but it is observed that cross-stream variation can be mitigated through strategies such as pitch-to-feather power control. It was found that overall fence performance was maximised by using turbines designed for moderately constrained (blocked) flows, with greater blockage than that based solely on fence geometry, but lower blockage than that based solely on the turbine and local flow passage geometry to balance the multi-scale flow phenomena around tidal fences.

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.

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