scholarly journals Some design guidelines to adapt a Darrieus vertical axis turbine for use in hydrokinetic applications

2021 ◽  
Vol 312 ◽  
pp. 08017
Author(s):  
Francesco Balduzzi ◽  
Pier Francesco Melani ◽  
Giuseppe Soraperra ◽  
Alessandra Brighenti ◽  
Lorenzo Battisti ◽  
...  
Keyword(s):  
Fluid Dynamic ◽  
Vertical Axis ◽  
High Water ◽  
Design Guidelines ◽  
Rotor Blades ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Geometrical Parameters ◽  
Technical Literature ◽  
Downstream Flow

The use of vertical-axis turbines is raising interest in the field of hydropower production from rivers or water channels, where suitable mass flows are available, without the need of high water jumps or large construction sites. Although many optimization studies on vertical-axis turbines have been carried out for wind applications, lesser examples exist in the technical literature regarding hydrokinetic turbines. In the latter case, the best trade-off between power output and low structural stress is more dependent on the fluid dynamic loadings rather than the inertial loadings, due to the higher fluid density and lower rotation speed. The present work shows the results of an industrial study case application, in which the design of a traditional three-blade Darrieus rotor has been adapted for operating in water flows via hydrokinetic technology. Some specific design rules will be discussed, showing the different concepts adopted for the machine layout in order to achieve the best efficiency and performance. Multiple geometrical parameters of the rotor configuration were involved during the analysis: the number of rotor blades, i.e. two or three blades, the rotor’s shape, i.e. traditional H-shape or unconventional L-shape, and the use of power augmentation systems. The analysis of the numerical results was focused on the following output targets: maximum power coefficient, optimal tip speed ratio (TSR), rotor thrust, blade normal force and the upstream and downstream flow field influence. The outcome of the study shows how the best configuration differs from the common solutions for wind application. Moreover, a high power enhancement can be achieved while guaranteeing a good compromise in terms of structural loads.

Numerical Analysis of the Overlap Effect Between Blades at Four-Bladed Rooftop VAWT

2012 ◽  
Author(s):  
H. Flores-Saldaña ◽  
A. Gallegos-Muñoz ◽  
N. C. Uzarraga-Rodriguez ◽  
V. H. Rangel-Hernandez
Keyword(s):  
Numerical Analysis ◽  
Wind Turbine ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine ◽  
Moment Coefficient ◽  
Mesh Model ◽  
The Moment

This work presents a numerical analysis of a four-bladed Rooftop vertical axis wind turbine (VAWT). The effects generated on the performance of turbine by the overlap variation between blades of wind rotor were analyzed. The numerical simulations were developed using commercial software based on Computational Fluid Dynamic (CFD). Each one of the models generated was built in a 3D computational model. A sliding mesh model (SMM) capability was used to present in dimensionless form the moment coefficient and power coefficient of the wind turbine based on the relationship between wind speed and rotor rotational speed. The results show that the aerodynamic performance is better with overlap between rotor blades, resulting in a significant increase in the moment coefficient and power coefficient. Having that in the cases of four-bladed Rooftop rotor with overlap both coefficients increase about 29% comparing with four-bladed Rooftop rotor without overlap between blades.

Performance of a Darrieus turbine on the roof of a building

2018 ◽  
Vol 42 (4) ◽  
pp. 341-349 ◽  
Author(s):  
Samson Victor ◽  
Marius Paraschivoiu
Keyword(s):  
Urban Areas ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Wind Generation ◽  
Speed Ratio ◽  
Cfd Analysis ◽  
Vertical Axis Wind Turbine ◽  
Tip Speed Ratio ◽  
General Rules

Various efforts have been made to introduce micro wind turbines in urban areas. Their onsite wind generation can be beneficial, but general rules about their ideal placement in terms of energy extraction need to be identified. This paper investigates the performance of a Darrieus turbine when installed on the roof of a building and offers a rare analysis of the synergy between the turbine and the building. This study focuses on computational fluid dynamic (CFD) analysis of a vertical-axis wind turbine mounted on the upstream edge of a building. The CFD methodology is validated by comparing the calculated performance with experimental data. Three different turbine positions at different heights are investigated to capture the Cp–λ curve sensitivity. Positions 1 and 2 are at the edge of the building, whereas position 3 is a few meters away from the edge, directed towards the geometric center of the building. To simulate realistic atmospheric wind conditions, an atmospheric boundary layer is imposed at the inlet. The results show that the power coefficient is higher compared with a standalone turbine and that the location of the turbine on the building clearly affects the value of the tip-speed ratio at maximum power coefficient.

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.

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

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.

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°.

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

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1446 ◽  
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.

Optimization of Aerodynamic Parameters of an Elliptical-Bladed Savonius Wind Rotor Using Multi-Objective Genetic Algorithms

2019 ◽  
Author(s):  
Nur Alom ◽  
Ranjan Das ◽  
Ujjwal K. Saha
Keyword(s):  
Genetic Algorithms ◽  
Lift Coefficient ◽  
Optimization Technique ◽  
Geometric Parameters ◽  
Rotor Blades ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Direct Optimization ◽  
Multi Objective ◽  
Augmentation Techniques

Abstract The Savonius wind rotor, a drag-based machine, despite having lesser efficiency has got several advantages such as low price, easy installation, better starting capability independency to wind direction. In order to enhance the performance of such rotor, several design modifications have been built by changing the geometric parameters such as overlap ratio, aspect ratio, tip speed ratio, number of rotor blades and effect of shaft and end plates. Apart from the various geometric parameters, several rotor blades and augmentation techniques has evolved to improve the performance of the Savonius rotor. This has been achieved by using a host of numerical and experimental methods. In the present investigation, the multi-objective genetic algorithms have been used to optimize the incoming velocity, and the torque and lift coefficient for a novel elliptical-bladed profile for maximizing the rotor power coefficient. The multi-physics solver ANSYS direct optimization technique has been used to implement the genetic algorithms. The results obtained from the genetic algorithms have been compared with the established results under identical conditions.

Numerical Modeling of Vertical Axis Wind Turbines

2014 ◽  
Author(s):  
Teresa Parra-Santos ◽  
Armando Gallegos-Muñoz ◽  
Miguel A. Rodriguez-Beneite ◽  
Cristobal Uzarraga-Rodriguez ◽  
Francisco Castro-Ruiz
Keyword(s):  
Mechanical Energy ◽  
Vertical Axis ◽  
The Self ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Tip Speed Ratio ◽  
Vertical Axis Wind Turbines ◽  
Selection Of ◽  
Rotor Axis

This paper aims to predict the performance of Vertical Axis Wind Turbine (VAWT), hence the modeling of kinetic energy extraction from wind and its conversion to mechanical energy at the rotor axis, is carried out. The H-type Darrieus turbine consists of three straight blades with shape of aerofoil attached to a rotating vertical shaft. The criterion on the selection of this kind of turbines, despite its reduced efficiency, is the easy manufacture in workshops. A parametric study has been carried out to analyze the camber effect on the non dimensional curves of power coefficient so that the self starting features as well as the range of tip speed ratio of operation could be predicted.

scholarly journals Determining Optimum Rotary Blade Design for Wind-Powered Water-Pumping Systems for Local Selected Sites

2021 ◽  
Vol 67 (5) ◽  
pp. 214-222
Author(s):  
Abdulbasit Mohammed ◽  
Hirpa G. Lemu ◽  
Belete Sirahbizu
Keyword(s):  
Wind Energy ◽  
Performance Optimization ◽  
Rotor Blade ◽  
Rotor Blades ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Blade Design ◽  
Pumping System ◽  
Water Pumping ◽  
And Performance

The design of a windmill rotor is critical for harnessing wind energy. In this work, a study is conducted to optimize the design and performance of a rotor blade that is suitable for low wind conditions. The windmills’ rotor blades are aerodynamically designed based on the SG6043 airfoil and wind speed data at local selected sites. The aerodynamic profile of the rotor blade that can provide a maximum power coefficient, which is the relation between real rotor performance and the available wind energy on a given reference area, was calculated. Different parameters, such as blade shapes, chord distributions, tip speed ratio, geometries set angles, etc., were used to optimize the blade design with the objective of extracting maximum wind power for a water pumping system. Windmill rotor of 10.74 m, 7.34 m, and 6.34 m diameter with three blades were obtained for the selected sites at Abomsa, Metehara, and Ziway in south-east Ethiopia. During the rotary blades performance optimization, blade element momentum (BEM) theory and solving iteration by MATLAB® coding were used.

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

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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