Darrieus-type Vertical Axis Wind Research Articles

Perancangan Turbin Angin Vertikal Modifikasi Darrieus Menggunakan Geometri Airfoil Naca 2414

The National Energy General Plan policy is one of the government's focuses on controlling the use of renewable energy in line with the development of the need for energy use for the community, especially in the electricity sector. Electrical energy is energy that is very important for human needs, where every human being is very dependent on electricity for their daily needs. Currently, there is a crisis of fossil resources, so renewable energy can be developed. One renewable energy that is easy to develop is a wind turbine by utilizing the energy of the wind that blows. Indonesia has started to pay attention to increasing the efficiency of electricity generation, especially wind power. The type of turbine planned is the Darrieus type vertical axis wind turbine (VAWT) using a modified NACA Airfoil 2414 geometry with variations in wind speed. At a speed of 7,61 m/s from the test results obtained the power produced by the turbine is 20,78 watts with a voltage of 11,61 Volts and an electric current of 1,79 Amperes and at 354 rpm generator rotation. from the results obtained, the higher the wind speed, the higher the rotation produced by the turbine.

Plasma actuator effects on the flow physics of dynamic stall for a vertical axis wind turbine

Darrieus type vertical axis wind turbines have several advantages over other wind turbines for local electricity generation in urban environments. However, the main aerodynamic challenge is the negative impacts of the dynamic stall phenomenon on the turbine performance. This study numerically scrutinizes the effects of plasma actuators on the dynamic stall control and performance improvement of a Darrieus turbine. For this sake, unsteady Reynolds-averaged Navier–Stokes equations are solved using a pressure-based finite volume method. The Suzen–Hoang plasma actuator model is employed to calculate the body forces attributed to the plasma actuator. First, the dynamic stall characteristics of the turbine blade with no plasma actuator are explored. Then, three plasma actuator configurations (i.e., inboard, outboard, and double-sided) are considered. According to the results of the clean blade, the aerodynamic performance mainly depends on the reverse Karman vortex formation at the onset of the down-stroke motion and counterclockwise vortex formation on the blade suction side. The results of plasma configurations indicate that the inboard and double-sided actuators enhance the turbine power output by 10%, while the outboard actuator effects are negligible. Moreover, the plasma actuator is effective only in the down-stroke motion of the blade. Results also show that the inboard and double-sided plasma actuators eliminate the reverse Karman vortex and significantly reduce the counterclockwise vortex size, increasing the lift force and connection point moment. Consequently, the inboard and double-sided plasma actuators remove the negative torque generation in azimuth angles of 135° to 180°, primarily responsible for the output power enhancement.

A Comparative Aerodynamic Analysis of NACA and NREL Aerofoils for Darrieus Turbines Using CFD

The selection of the aerofoil plays a crucial role in achieving optimum power output, especially for the inherently low-efficient turbines, such as the Darrieus wind turbine. For this purpose, different aerofoils belonging to NACA and NREL families have been investigated in terms of the aerodynamic performance, comparatively. Although NREL aerofoils are mainly utilised for the Horizontal Axis Wind Turbines, in the present study, their effect on the Darrieus type Vertical Axis Wind Turbine has been examined. In this point of view, the influence of the various aerofoils and their thickness on the turbine performance in different operating ranges have been evaluated using Computational Fluid Dynamics (CFD). Furthermore, by considering the low and high tip speed ratios, the instantaneous blade torque coefficient, and the contours of the pressure coefficient for the selected aerofoils have been analysed to provide further understanding. The research findings show that the conventional aerofoils, such as NACA0015 and NACA0021, illustrate better power output at optimum and high tip speed ratios, while the NREL aerofoils, such as S814 and S825, are able to increase the torque generation at the relatively low tip speed ratio regions. Even though this situation makes the NREL aerofoil more desirable to design a self-starting Darrieus turbine, NREL aerofoils lost their advantages due to the higher efficiency loss at the higher tip speed ratios. In addition to this, the thicker aerofoils, such as NACA0021 and S814, yield more power output at the low tip speed ratio compared to their counterpart profiles as a result of the high pressure difference achieved between their suction and pressure sides.

Analysis of the Performance of The Four-Blade Darrieus Wind Turbine at the Jamik Bukit Asam Mosque Complex Tanjung Enim South Sumatra

Several types of renewable energy have been developed, such as solar energy, biomass, hydro energy, geothermal, and wind energy. Wind energy is an up-and-coming alternative and renewable energy. Wind energy is more environmentally friendly than available energy sources and has more accessible operational and maintenance costs. Indonesia has a relatively small natural wind energy potential because the wind speed in Indonesia is on average 3-6 m/s due to its location. Geographically, it is located in the equatorial area, especially the Muara Enim area, South Sumatra. This study aims to design a prototype the four-blade darrieus type vertical axis wind turbine (VAWT) needed for the utilization of wind energy which is used for Coffee Shop electricity needs at the Jamik Bukit Asam Tanjung Enim Mosque complex, South Sumatra, with the conclusion that the wind turbine, wind turbine rotation, the magnitude of the output voltage and The current generated significantly affects the wind speed in the area.

Numerical evaluation of optimum tip speed ratio for darrieus type vertical axis wind turbine

Usage of electric energy keep on increasing due to social and industrial advancement. Various types of sources are used to fulfill the energy needs. Wind energy is also a source which fulfills a part of electric energy needs with the help of wind turbine. In this study, darrieus type vertical axis wind turbine is used for its great potential in application to its structural advantage and omni-directionality. Tip Speed ratio (TSR) is one of the major parameter which effects the performance of darrieus wind turbine. Analysis of darrieus wind turbine is evaluated by varying Tip Speed Ratio (TSR) from 0 to 3 m/sec due to regional wind speed with a duration of 0.2 m/sec along with the validation of mesh independency and time independency. From the numerical analysis, Tip Speed ratio (TSR) of 1.8 shows the better performance with minor domain losses for low wind regional wind speed.

Optimization of Straight-bladed Darrieus type vertical axis wind blade for low wind speed

Straight-bladed Darrieus blade is a type of vertical axis wind turbine that requires low wind speed to operate but is considered less efficient due to conventional blade geometry. To increase its performance by means of dynamic torque, the study used a statistical method, central composite design, through DesignExpert software. The computational fluid dynamics (CFD) through SolidWorks Reynolds-Averaged Navier Stokes Equation (RANS) k – epsilon turbulence model was used to simulate the Design of Experiments. The study was composed of two phases, namely 2D and 3D simulations. The 2D simulation studied the effect of varying the camber, camber location, and thickness to the dynamic torque, while the 3D simulation varied the blade height, rotor radius, and materials. The camber’s optimal conditions, camber location, and thickness in 2D simulations are 4.75%, 45%, and 15.50% of the chord, respectively. These optimal design values could reach the dynamic torque equivalent to 60.6571 Newton-meter. Meanwhile, the blade height and rotor radius of the 3D simulations have optimal design values of 4.41 meters and 4.75 meters, respectively. These optimal values could increase the dynamic torque to 2310.01 Newton-meter. The dynamic torque of the optimal design obtained a 133% significant increase compared to the conventional blade. Thus, the research has proven the increase in the Darrieus Wind turbine’s performance by varying its blade geometry.

Numerical Investigation of a Vertical Axis Wind Turbine Performance Characterization Using New Variable Pitch Control Scheme

Abstract A double multiple streamtube model coupled with variable pitch methodology is used to analyze the performance characteristics of a small-scale straight-bladed Darrieus type vertical axis wind turbine (SB-VAWT). The numerical study revealed that a fixed pitch of −2.5 deg could greatly enhance the performance of the wind turbine. However, no improvement is observed in the starting torque capacity. Furthermore, the performance of upwind and downwind zones has been investigated, and it is found that the VAWT starting capacity is improved by increasing/decreasing the pitch angle upwind/downwind of the turbine. To optimize the performance, four cases of variable pitch angle schemes of sinusoidal nature were examined. The parameters of the sinusoidal functions were optimized using differential evolution (DE) algorithm with different cost functions. The results showed improvement in the power coefficient, yet with low starting capacity enhancement. Among the objective functions used in DE algorithm, the negative of the average power coefficient is found to lead to the best starting capacity with moderate peak power coefficient.

Performance investigation of a new Darrieus Vertical Axis Wind Turbine

In present work, a new configuration of Darrieus type Vertical Axis Wind Turbine (VAWT) is introduced, and its aerodynamic performance is examined using three-dimensional numerical simulation by the solution of Reynolds averaged Naiver-Stokes equations. In comparison to each other, straight-blade VAWTs have higher average output torque and are simpler to manufacture while helical-blade VAWTs deliver non-oscillatory and smoother torque. To include advantages of both types of Darrieus VAWTs, a new straight-blade turbine is proposed which in general performs better than helical-blade VAWT. This turbine, called three-part-blade or simply 3-PB VAWT, includes straight blades where each of them is vertically cut into three parts. The objective of this paper is to show that while the proposed turbine is simple to manufacture, its performance is better than that of helical-blade VAWT. Present simulation is validated using experimental data. Having compared performance of the proposed turbine with a helical-blade VAWT, it is shown that 3-PB VAWT produces 6.06% higher average of total torque coefficient at low Tip Speed Ratio (TSR) of 0.44, and 158.19% at high TSR of 1.77. Based on these results, it is strongly recommended to use 3-PB VAWT considering its better aerodynamic performance and low cost of production.

Numerical investigation of Darrieus wind turbine with slotted airfoil blades

Abstract Low starting torque is considered as one of the major drawbacks of Darrieus type vertical axis wind turbine (VAWT). Design optimization to overcome this problem by modifying the airfoil geometry has received great attention by the wind energy community. Moreover, efforts have been directed towards augmenting the power coefficient of the turbine. In the present work, the effect of employing slotted airfoil as turbine blade on the performance and starting characteristics has been investigated. The slot parameters; slot location, angle of inclination, and dimensions, were optimized for NACA 0018 airfoil which is commonly used in Darrieus turbines. The flow over the turbine was modelled using ANSYS-FLUENT code. The main observations of the present study show that the VAWT with slotted Airfoil (SA) has a lower optimum tip speed ratio (TSR) compared with the Baseline (BL) turbine. This is associated with the ability to generate higher torque at lower rotational speeds. The analysis of the aerodynamic behavior of the SA turbine shows that the airfoil slot delays the separation at high angles of attack, and therefore improves the torque and power coefficient at low TSR.

Performance assessment of Darrieus wind turbines with symmetric and cambered airfoils

During the operation of a Darrieus type vertical axis wind turbine (VAWT), the blade sections are subjected to different flow velocities and incidences that can be converted to mechanical power with varying efficiency depending on the airfoil. The goal of the present study is to emphasize the advantages and the drawbacks of the use of symmetrical, cambered, and laminar airfoil for a typical Darrieus type VAWT. The NACA 0018, FX63-137 and SNLA 18/50 airfoils were selected for this study.

Numerical and Experimental Study on Performance Enhancement of Darrieus Vertical Axis Wind Turbine With Wingtip Devices

Darrieus type vertical axis wind turbines (VAWT) are being used commercially nowadays; however, they still need to improve in terms of performance as they work in an urban environment where the wind speeds are low and the gusts are frequent. The aerodynamic performance of Darrieus turbine is highly affected by the wingtip vortices. This paper attempts at analyzing and comparing the performance of Darrieus with the use of various wingtip devices. Attempts have also been made to find out optimal working parameters by studying the flow through turbines with different tip speed ratios and different inlet wind speeds. A comparative computational fluid dynamics (CFD) simulation was performed on a small-scale, straight-bladed Darrieus rotor vertical axis wind turbine, with a large stationary domain and a small rotating subdomain using sliding mesh technique. Comparison of the performance of end tip device that can be used against a baseline rotor configuration is done, with the aim of identifying the best tip architecture. The main focus lies on building an experimental setup to validate the results obtained with the CFD simulation and to compare the performance with and without wingtip device. VAWTs with wingtip device show very promising results compared to the baseline model.

Assessment of performance enhancement of a semi-submersible vertical axis wind turbine with an optimized Darrieus rotor

Increasing efforts are currently being devoted to develop floating vertical axis wind turbines (VAWTs), due to their potential to reduce the cost-of-energy. Optimization of rotors is favorable to increase the power capture and mitigate structural loads. In the DeepWind project, a baseline Darrieus type vertical axis wind turbine (VAWT) was first developed, followed by an optimized rotor. In this study, these two different rotors are adapted to a semi-submersible platform to achieve two floating VAWTs. The performance enhancement of the floating VAWT with the optimized rotor is evaluated by performance comparison with the floating VAWT with the baseline rotor. Numerical simulations are conducted using a fully coupled aero-hydro-servo-elastic simulation tool in time domain, under turbulent wind and irregular waves. Numerical analyses indicate that the floating VAWT with the optimized rotor greatly improves the performances with respect to power production, global platform motions, mooring line tensions, and especially tower base bending moments. The annual power production of the floating VAWT with the optimized rotor is improved by 11.3% as compared to that of the floating VAWT with the baseline rotor. However, the variations of flapwise and edgewise bending moments along the blades are not improved for the optimized rotor, which might cause severe fatigue damage, and should be considered during the optimization of blades for VAWTs.

A comprehensive analysis of solidity for cambered darrieus VAWTs

Wind energy technology has seen steady growth in the energy market as a clean, renewable source of energy. This has brought attention to areas with moderate wind energy potentials. Darrieus type Vertical Axis Wind Turbines (VAWTs) allow capturing of this potential for energy production at a cost-effective scale. To improve the performance of these turbines their design needs to be optimized. With better manufacturing methods currently available cambered blades are being investigated to improve the performance of these turbines. In particular, turbine solidity is investigated in this paper due to different airfoil chord lengths and different number of blades. The analysis is conducted following high fidelity CFD modeling in unsteady, turbulent regimes in Arbitrary Lagrangian Eulerian formulation accounting for the sliding/rotating rotor's domain configuration that emphasizes the role of rotor blades interaction. The study showed that low solidity turbines with cambered blades operate at low coefficients of performance (CP) over a large range of tip speed ratios (TSRs). High solidity turbines, with solidity close to unity, have much higher CP, but at smaller TSRs and a short range of TSRs. Medium solidity turbines, as well as turbines with solidity greater than unity, are faced with considerable interaction which compromises their operation at TSRs as low as one. The larger chord length helps improve the torque production of the turbine. The change in number of blades leads to a large dispersed wake behind the rotor which is unfavorable for deployment of an array of turbines.

Optimizacija vetroturbine sa vertikalnom osom upotrebom genetskih algoritama i CST parametrizacijom aeroprofila

Darrieus type vertical axis wind turbine (VAWT) is optimized using the genetic algorithm (GA). The airfoil shape is parameterized using the Class-Shape Transformation (CST) method. The double multiple stream tube (DMST) method with the Gormont dynamic stall modification is used for the calculation of the VAWT performance parameters. Once the numerical codes are validated using available experimental results, the airfoil parameters are varied as to achieve the optimum value of the genetic algorithm fitness function.

Starting torque improvement using J-shaped straight-bladed Darrieus vertical axis wind turbine by means of numerical simulation

In this study a 3 kW straight–bladed Darrieus type Vertical Axis Wind Turbine (VAWT) is investigated numerically using OpenFOAM computational fluid dynamic package. The newly proposed J-Shaped profile is used as the blade airfoil in the simulation. The J-Shaped profile is designed by means of eliminating a fraction of pressure side of Du 06-W-200 airfoil. The main purpose of this investigation is the improvement of the VAWT starting torque using J-shaped profile. The power curves for both conventional and J-shaped profiles are calculated and the torque variation is obtained at different azimuth angles. In addition, the vorticity and pressure field surrounding the wind turbine is presented. The results indicate that the performance of turbine is optimized for J-shaped profile which eliminates the pressure side of airfoil from the maximum thickness toward the trailing edge. Moreover, by employing this J-Shaped profile, the wind turbine performance is intensified TSRs and self-starting of turbine is improved.

Modern small wind turbine design solutions comparison in terms of estimated cost to energy output ratio

This paper presents a series of estimations performed in order to establish the actual cost-effectiveness of three different small wind turbines (SWTs) design solutions. Each of them was evaluated and based on their power curves and installation costs, using wind data from a numerical weather prediction (WNP) model, a return on investment (ROI) period was calculated. The chosen turbines are: a standard three bladed horizontal axis wind turbine (HAWT), an advanced diffuser augmented HAWT and a Darrieus type vertical axis wind turbine (VAWT). The conclusions drawn from this study entertain the idea that from the economical point of view, a price reduction of SWT systems is more important than aerodynamic complexity and efficiency.

Study of Characteristics of Darrieus-type Straight-bladed Vertical Axis Wind Turbine by Use of Ailerons

This paper presents a new starting assist method for Darrieus turbines using movable ailerons. To confirm the effect of the ailerons, we conducted wind tunnel tests to find the starting torque, starting wind speed, and load torque characteristics. The tested turbine has four blades, and the tested ailerons are fixed-angle and movable types. The movable ailerons increase the starting torque, thereby reducing the wind speed for startup. When a movable aileron is used, the load torque at low rotational speed is increased. Furthermore, the load torque of the turbine is roughly equal to the bare blade turbine at high rotational speed. 2007), and were found to provide more efficiency than symmetrical blades in water channel tests (Kihoh and Shiono, 1992). To investigate how the WT characteristics were changed by the ailerons, the ailerons were initially mounted at a fixed angle (fixed- aileron blades), and this arrangement was observed for the effect of the ailerons on the starting torque of the WT. The fixed-aileron blade experiment showed that the starting torque is increased in some of the position angles and decreased in other position angles, but the mean starting torque is not greatly increased. Therefore, we propose movable ailerons that are equipped with an extension- retraction mechanism. A wind tunnel experiment showed that movable ailerons increase the starting torque of the WT and that the wind speed needed for startup is decreased. Self-starting is not the only important feature of a WT; load characteristics are just as important. Therefore, the influence of the movable ailerons on load characteristics is also examined. Due to the effects of the fittings for controlling the angle of the movable aileron in the model constructed here, it was noted that at high rotational speed the ailerons reduce the WT output to below the power obtained in a model whose blades have no ailerons (bare blades). Therefore, a method is demonstrated for overcoming this.

Aerodynamic performance and characteristic of vortex structures for Darrieus wind turbine. II. The relationship between vortex structure and aerodynamic performance

In this paper, transient computational fluid dynamics (CFD) simulations of a straight-bladed Darrieus type vertical axis wind turbine were performed by means of an in-house CFD code. The Spalart-Allmaras turbulence model was implemented in the numerical code for the turbulence. Particular emphasis was placed on effect of interaction between vortices and blades on the aerodynamic performance of the simulated turbine at different tip speed and solidity ratios. The obtained results suggested that vortices were shed from previous blade passages and the close encounter of a rotor blade with these vortices can have a considerable impact on power coefficient of the simulated turbine during operation at different tip speed ratios. As a result, possible reasons for the changes in the behavior of this type of turbine due to the variation of tip speed ratio and solidity were proposed.

Economical Darrieus straight bladed vertical axis wind turbine for renewable energy applications

AbstractIn remote and stand alone applications, the simple straight bladed Darrieus type vertical axis wind turbine is very practical due to its simple design and low cost of construction. It has the potential to compete effectively with the more widely used horizontal axis wind turbines. This project explores a Darrieus type vertical axis wind turbine, adapted for domestic electricity generation. Design, construction and modelling of a three-blade vertical axis wind turbine with 305 cm long blades, 55 cm chord length, which formed a symmetrical airfoil of National Advisory Committee for Aeronautics (NACA 0018) profile, was performed in this study to demonstrate how used materials can be recycled to produce an economically feasible Darrieus type vertical axis wind turbine that can be utilised to produce usable electrical power. The double multiple streamtube model was used to reproduce this turbine. Materials used were chosen for practicality, availability within the southern Caribbean islands of Trinidad...

Comparative study of a three-bucket Savonius rotor with a combined three-bucket Savonius–three-bladed Darrieus rotor

The vertical axis wind turbines are simple in construction, self-starting, inexpensive and can accept wind from any direction without orientation. A combined Savonius–Darrieus type vertical axis wind rotor has got many advantages over individual Savonius or individual Darrieus wind rotor, such as better efficiency than Savonius rotor and high starting torque than Darrieus rotor. But works on the combined Savonius–Darrieus wind rotor are very scare. In view of the above, two types of models, one simple Savonius and the other combined Savonius–Darrieus wind rotors were designed and fabricated. The Savonius rotor was a three-bucket system having provisions for overlap variations. The Savonius–Darrieus rotor was a combination of three-bucket Savonius and three-bladed Darrieus rotors with the Savonius placed on top of the Darrieus rotor. The overlap variation was made in the upper part, i.e. the Savonius rotor only. These were tested in a subsonic wind tunnel available in the department. The various parameters namely, power coefficients and torque coefficients were calculated for both overlap and without overlap conditions. From the present investigation, it is seen that with the increase of overlap, the power coefficients start decreasing. The maximum power coefficient of 51% is obtained at no overlap condition. However, while comparing the power coefficients ( C p) for simple Savonius-rotor with that of the combined configuration of Savonius–Darrieus rotor, it is observed that there is a definite improvement in the power coefficient for the combined Savonius–Darrieus rotor without overlap condition. Combined rotor without overlap condition provided an efficiency of 0.51, which is higher than the efficiency of the Savonius rotor at any overlap positions under the same test conditions.