H-Darrieus Turbine Research Articles

Design of a recirculating water channel for the development of a hydrokinetic turbine

This study presents the design, construction, and operational details of an experimental recirculating water channel dedicated to the assessment of hydrokinetic turbines, including a propeller-type turbine and a H-Darrieus turbine, since it offers a controlled testing environment. The recirculating water channel had overall dimensions of 5 m in length, 0.35 m in width, and 0.5 m in depth, it allows for the replication of various water flow conditions and permits a maximum achievable flow velocity of 0.6 m/s, which closely resembles real-world scenarios. Afterwards, a propeller- type turbine and a H-Darrieus turbine underwent characterization within the channel, and a performance curve constructed through the coefficient versus the blade tip speed ratio (TSR) revealed a peak efficiency of 0.2129 at a TSR of 2.952 for the propeller turbine, and a higher peak efficiency of 0.3076 at a TSR of 0.38 for the H-Darrieus turbine. The versatility of this experimental setup makes it a valuable platform for in-depth performance studies of hydrokinetic turbines. This water channel and its systematic characterization process represent a vital resource for conducting efficiency and behavior analyses across a wide range of operational parameters related to hydrokinetic turbine technologies.

Impact of Blade and Solidity on the Performance of H-Darrieus Hydrokinetic Turbines by CFD Simulation

Purpose: In the present work, the 2D design of H-Darrieus turbines with a diameter of 900 mm and NACA blades 0018, 0025, 2415, and 4415 has been carried out for the solidity values of 0,5; 1 and 1,5. In order to know its maximum performance. Method/design/approach: The 2D simulations were developed with the ANSYS® FLUENT package in the transient state, varying the angular velocity (ω) for a peak velocity ratio (TSR) of 1 to 7 and the SST K-ω turbulence model, for a constant water flow rate of 1 m/s. This in order to know the results of the torque (Nm) generated and thus calculate the power coefficient (Cp). Results and conclusion: The NACA 0018 blade reached a power coefficient of 0,604 for a solidity of 0,5, followed by NACA 2415 blade at the same solidity with a maximum Cp of 0,594. On the other hand, the NACA 0025 blade for solidity of 1 reached a maximum Cp value of 0,570, while the NACA 4415 profile with a solidity of 1,5 obtained a maximum value of 0.495. Research implications: These results of maximum Cp values were given in a TSR range of 2 to 4 with a mean value of 3,5 for NACA profiles 0018 and 2415. Thus, evidencing the behavior of this type of turbine reaching maximum values to then begin to decrease. Originality/value: The present work contributes to the understanding of the impact of geometrical parameters on the operating coefficient of H-Darrieus.

Cavitation study of H-Darrieus hydrokinetic turbines via numerical simulations

This paper presents a parametric study of H-Darrieus turbines in cavitating conditions. The objective of this work is to assess the impact of cavitation on turbine performances for a wide variety of configurations and under various operating conditions. A better insight on the most “cavitation-friendly” turbine is provided by determining the optimal design parameters in terms of solidity, deployment depth, number of blades and blade pitch angle. Such design parameters are studied here and help to identify and analyse the inception and effects of cavitation. Two-dimensional URANS numerical simulations are carried out within Star-CCM+ at a Reynolds number of 107 based on the turbine diameter. The cavitating conditions simulated in this paper correspond to near-surface deployments at free-stream velocities ranging from 2 to 3 m/s. In a first phase, the solidity is varied from 0.1 to 0.7 while the tip-speed ratio is varied accordingly for optimal power coefficient. It is shown that a higher solidity turbine operating at a lower tip-speed ratio is beneficial in cavitating conditions due to the low effective velocity on the blades. The chord-to-radius ratio is varied in the second phase of this study. Turbines with 1, 3, 6 and 9 blades for a constant solidity of 0.6 are simulated and the results show that a larger chord-to-radius ratio is detrimental in cavitating conditions. Thus, the high curvature effects are to be avoided by using a larger number of blades for a given turbine solidity. The third and final phase of this study simulates turbines where the blade pitch angle was varied from −6° to +2° for a medium turbine solidity of 0.3. The small negative blade pitch angles of −2° and −4° show promising results where cavitation is greatly reduced, showing an improvement on power coefficient of 45 % for a blade pitch angle of −4° compared to the no blade pitch angle case at a cavitation number of 35. Overall, this paper concludes on the fact that the blade’s effective velocity and angle of attack are the key parameters controlling cavitation and that a combination of the studied design parameters should be considered to completely avoid cavitation inception or limit its detrimental effect on performance.

Assessment of icing effects on the wake shed behind a vertical axis wind turbine

To shed light on the effect of the icing phenomenon on the vertical-axis wind turbine (VAWT) wake characteristics, we present a high-fidelity computational fluid dynamics simulation of the flow field of H-Darrieus turbine under the icing conditions. To address continuous geometry alteration due to the icing and predefined motion of the VAWT, a pseudo-steady approach proposed by Baizhuma et al. [“Numerical method to predict ice accretion shapes and performance penalties for rotating vertical axis wind turbines under icing conditions,” J. Wind Eng. Ind. Aerodyn. 216, 104708 (2021)] was implemented, which enables the utilization of appropriate approaches for handling turbine rotation and turbulence prediction for each solver. Proper orthogonal decomposition (POD) was utilized to perform a deep analysis of the wake and aerodynamics of the wind turbine for the clean and iced turbines with large eddy simulation turbulence method. Icing causes the leading edge vortex and trailing edge vortex to separate faster than the clean case resulting in a steeper drop in the power coefficient. As for POD modes, those of the streamwise component of velocity illustrated more difference in the amount of modal energy especially at the first modes proving that the icing phenomenon mainly affects the vortex shedding of the flow structures with larger energy and size. The modes of the transversal component of velocity of the clean and iced cases demonstrated more similarity in essence, which could also be understood from the accumulated energy curve.

Assessment of fairing geometry effects on H-Darrieus hydro turbine performance using 2D URANS CFD simulations

This study aims to enhance the hydrodynamic efficiency of the fairing system and increase the power coefficient Cp of a three-bladed H-Darrieus turbine by investigating various geometries and configurations in comparison to the reference model. 2D CFD modeling and URANS calculations along with the k-ω SST turbulence model are employed for conducting parametric studies. The analysis focuses on assessing the geometric parameters of the fairing system that affect its behavior, such as the angle of incidence α and the chord length C of the fairing profile. It was found that at x/C=0.39934, the normalized power coefficient Cp/Cp,max of H-Darrieus equipped with the fairing amounts to 0.967581, whereas at x/C=0.750825, it attains Cp=0.486284. A power coefficient of Cp=0.621315 is achieved when an angle of attack α=10∘ and a tip speed ratio λ=2 are combined. In addition, the optimal operating point Cp for both fairing profiles is λ=2. In addition, maximum performance is reached at α=18∘ for the Eppler-420 profile, with a peak Cp=0.662, whereas the S1223-RTL profile demonstrates optimal performance at α=30∘ , with a peak Cp=0.728. Differences in the maximum and minimum ΔP∗ values between the Eppler-420 and S1223-RTL are also noted. It is observed that the S1223-RTL profile displays lower drag Cd and lift Cl coefficient values than the Eppler-420 profile up to α≈22∘. finally yet importantly, the highest Cp is observed at a chord length of C=4.0R, while the lowest occurs at a chord length of C=2.5R. Both Cd and Cl exhibit relative constancy for chord lengths shorter than C=4.0R.

CFD comparison of 2D and 3D aerodynamics in H-Darrieus prototype wake

In the present study, a comparative assessment is conducted to evaluate the outcomes derived from two-dimensional (2D) and three-dimensional (3D) computational fluid dynamics (CFD) models utilizing the unsteady Reynolds-averaged Navier–Stokes (URANS) approach. The focus lies on the aerodynamic performance of the H-Darrieus vertical axis wind turbine, which has been the subject of numerous numerical investigations since 2010. The k−ω shear stress transport (SST) turbulence model is employed to replicate the flow structures evolving in the turbine wake.The maximum power coefficients attained through 2D and 3D modeling are reported as Cp=0.4016 and Cp=0.5734, respectively, at a tip speed ratio (λ) of 3.0976. The maximum 2D and 3D absolute errors, corresponding to the evaluation of the power coefficients, are determined to be 14.9714% and 29.1582%, respectively. These errors are calculated at λ=2.5183 and λ=3.0976. The parametric study conducted herein reveals that the range of the power coefficient enhancement, considering 3D aerodynamic effects, surpasses that obtained from 2D calculations. In 3D modeling, this range is delineated between λ=1.85 and λ=3.10, whereas, in 2D modeling, it is defined by the interval bounded by λ=2.05 and λ=3.10. The essential contours for comparing the 2D and 3D approaches and for characterizing the flow structures developing around the H-Darrieus turbine are generated and analyzed.

Numerical comparison and efficiency analysis of three vertical axis turbine of H-Darrieus type

Hydropower is an important source of energy in Latin America. Many countries in the region, including Brazil, Peru, Colombia, and Chile, rely heavily on hydropower plants to meet their energy needs. However, there are also challenges related to the use of hydropower in the region, such as the construction of dams that can have negative impacts on ecosystems and local communities. A new alternative is the production of energy through hydrokinetic turbines because they are a clean and renewable energy source that does not emit greenhouse gases. In addition, its production is predictable and can be generated in a variety of environments, from coasts to rivers and canals. Within the hydrokinetic turbines are the H-Darrieus turbines although they are still under development, they are seen as an important opportunity to diversify the energy matrix and reduce dependence on fossil fuels. The main purpose of this study is to determine and compare the efficiency of three Darrieus H-type vertical axis hydrokinetic turbines numerically. The turbines were configured with different solidities. The NACA 0018 profile was used for the turbine design. The study was carried out using the ANSYS® Fluent 2022R2 software, two-dimensional (2D) simulations set up constant operating conditions. Rotation speed variations have been set between 21 and 74 RPM with 10 rpm increments. Furthermore, the General Richardson extrapolation method is used for the analysis of mesh convergence, monitoring the turbine power coefficient as a convergence parameter. The numerical results show that the turbine H-Darrieus with a solidity of 1.0, a wider operating range, and lower power and torque coefficient. At low TRS, the largest solidity provided the best efficiency and the greatest self-starting capability, but it also had the smallest operating range

Using deep generative adversarial network to explore novel airfoil designs for vertical-axis wind turbines

Wind energy has emerged as an attractive alternative to the current fossil fuel-based energy mix. In this context, small-scale H-Darrieus vertical-axis wind turbines (VAWTs) combine interesting characteristics for harvesting wind energy in urban-like conditions. Still, H-Darrieus turbines are reported to experience relatively low aerodynamic efficiency. Even though several devices have been proposed to increase the aerodynamic performance of H-Darrieus turbines, the literature seems to overlook the potential of specifically designed airfoil shapes. In part, this is a by-product of different shortcomings related to the most common airfoil parameterization methods, such as restricted shape variability, high dimensionality, discontinuous spaces, and/or non-orthogonal parameters. Seeking to overcome these drawbacks altogether, we investigate here the benefits of the Bézier-GAN as an airfoil parameterization method for H-Darrieus turbines. For that, we use computational fluid dynamics (CFD) simulations along with sensitivity analysis, metamodeling, and optimization strategies. The results show that the Bézier-GAN integrates nicely with the proposed framework, substantially reducing the total computational cost of the experiment. By expanding the bounds of the latent design space, we can easily explore novel airfoil designs. The sensitivity analysis clearly indicates a lack of two-way interactions between the latent variables, which further simplifies both the metamodeling and the optimization processes. The optimal geometry increased the turbine performance by 20.5% relative to a NACA 0015 and by 9.1% relative to a NACA 0021—two common airfoil shapes used in H-Darrieus turbines. Interestingly, the optimal geometry was found outside the original bounds of the design space, further confirming that the search for novel airfoil designs may open the way for better aerodynamic performance of small-scale H-Darrieus turbines.

A Numerical Procedure for Variable-Pitch Law Formulation of Vertical-Axis Wind Turbines

A numerical procedure was developed to determine a variable-pitch law that maximized the performance of a vertical-axis wind turbine (VAWT). The methodology was based on the determination, for each blade, of the angle of attack maximizing the stationary aerodynamic efficiency at prescribed azimuthal positions. The angles of attack were determined by means of a panel method with a low computational effort, and the methodology was implemented in Matlab® software (version R2021a) allowing us to achieve in real time a variable-pitch law suitable for the turbine geometry. The variable pitch law was validated by considering its effect on the torque of a 2D model of an H-Darrieus turbine. U-RANS analyses were carried out with a K−ωSST model and a sliding-mesh technique was used to prescribe the blade motion around the shaft and pitch motion. Results showed how the variable-pitch law delayed the dynamic stall and improved the aerodynamic performance considerably.

Numerical Study of H-Darrieus Turbine as a Rotor for Gravitational Vortex Turbine

The main objetive of this study is to compare numerically the torque generated at 50, 75, 100, and 125 rpm by H-Darrieus turbine as a rotor for Gravitational Vortex Turbine. The rotational flow into the gravitational vortex turbine tank helped to decrease the negative torque in H-Darrieus rotor. The study was developed in ANSYS® CFX, where the model was configured at constant operating conditions. The highest torque was 0.117 Nm at 50 rpm, and the torque decreased with increasing rpm. The H-Darrieus works with increasing lift force, however, the rotor inside the Gravitational Vortex Turbine interacts with drag force.

Investigation of the hydrogen production potential of the H-Darrieus turbines combined with various wind-lens

In this study, it is aimed to investigate of the hydrogen production potential of the H-Darrieus turbines combined with various wind-lens. In the calculations, various wind-lens H-Darrieus models have been considered as diffuser (M1), nozzle diffuser (M2), diffuser brim (M3), and nozzle diffuser brim (M4). The numerical analyses have been performed with ANSYS-fluent software program. Firstly, the power (CP) and torque (CT) coefficients for M1, M2, M3 and M4 turbine models have been computed and compared with the conventional bare turbine (B1). Secondly, the annual hydrogen production (kg/year) for M1, M2, M3 and M4 turbine models and bare turbine (B1) have been conducted in different tip speed ratio (TSRs). The annual theoretical hydrogen potentials produced by the B1, M1, M2, M3 and M4 models per single turbine have been obtained as 1.74, 1.88, 1.84, 2.82 and 2.5 kg, respectively. As a result, the best hydrogen production (kg/year) potential has been determined for diffuser brim (M3) model according to the other models.

Start-up considerations for a small vertical-axis wind turbine for direct wind-to-heat applications

Renewable production of space and water heating is needed for a sustainable society. The rotating shaft of a vertical-axis wind turbine can be equipped with a paddle wheel-style mixing impeller to directly heat a fluid by agitating or stirring the fluid. A Darrieus vertical-axis wind turbine, operating at or near its nameplate power capacity, is able to perform this function reliably as it is producing significant amounts of power; however, an autonomous wind-to-thermal system presents a challenge due to the difficulties associated with the start-up process of this type of turbine. The start-up difficulty is quantified herein by using a set of well-referenced vertical-axis wind turbine start-up data to derive the turbine’s torque and power values for each rotational velocity data point. It is shown that the turbine produces minimal positive torque during an extended region of operation around tip-speed ratio λ=1. A fluid-agitation thermal generator is considered by employing fluid mixing theory to compute the torque of a conceptual mixing impeller for different impeller diameters and styles. A thermal generator impeller is sized based on the derived experimental values and operational characteristics of the vertical-axis wind turbine data set. Thermodynamic analysis for the conceptual fluid-agitation generator shows that for an enclosed fluid volume ▪ = 1L, a fluid temperature rise of approximately ΔT=5°C can be achieved during one hour of system operation. The results demonstrate the potential of H-Darrieus turbines as renewable heat generating devices, while highlighting the need for careful system design to achieve successful start-up.

Power augmentation in H-Type Darrieus wind turbine using wind lens

Abstract The need for clean, sustainable and cost-effective energy sources leads to the installation of wind turbines with advanced technologies. One of the main parameters which govern the productivity of any wind turbine is its power generation capacity. The higher the incoming wind speed, the more the power generation, but the challenges faced by wind turbine is in low wind speeds. Hence, it becomes important to boost the efficiency of wind turbine with modified designs for lower wind urban regions. The prime objective is to boost the power production of a conventional two-bladed VAWT with the application of convergent-divergent type wind lens. Ansys CFX is employed for numerical analysis of flow around the rotor of straight bladed H-Darrieus turbine. Different turbulence models are analysed and SST k-ω model is well validated with experimental result. Power coefficient values are evaluated at a range of 0.5 to 3 tip speed ratios in both cases. Simulation result is validated with experimental results in terms of power coefficient. Computational result is validated with 4% error and 2% error for simple VAWT and VAWT with wind lens respectively. The results show an enhancement of 2.6 times the power coefficient values of conventional VAWT.

Numerical analysis of wake turbulence between hybrid tidal turbine and hypothetical actuator cylinder for shallow water with low velocity conditions

Towards modernisation of the technological era, electricity demands have been an issue. Although the supply of electrical energy from the renewable sources are increasing, it is still not sufficient to offset the carbon production. Malaysia as a developing country needs ample of supply of electrical energy. As most of the current electrical energy for the country are being produced by non renewable sources, the Malaysian government have started looking into renewable options to produce electrical energy. There are various sources of energy that are available in Malaysia such as solar, natural gas, petroleum, ocean energy and many more. This paper is focused on the tidal energy which is an ocean energy that can produce electrical energy by using the power of tide. This research explores the hybrid turbine design which is a type of vertical-axis tidal turbine that combines two distinct type of devices, namely Savonius and H-Darrieus turbines. Hybrid turbine is useful as it helps to overcome the limitation of individual turbine and also be able to produce energy at a low water velocity. Numerical analysis is employed to investigate the wake recovery behaviour and turbulent mixing due to the positioning of the device using Ansys CFD Fluent. By understanding the general wake characteristics produced by each device, proper planning can be done to configure these devices in an array for future planning. The simulation result shows that the hybrid turbine utilising NACA0015 and NACA0018 with nested configuration demonstrates faster velocity recovery compared to NACA0021. The turbulence wake results also provides a promising output which shows the acceleration of flow at the downstream region for hybrid nested NACA0015 and NACA0018 are more narrow compared to NACA0021. The result of this simulation has also been validated with published data. In a nutshell, the NACA blade design not only affects the performance of the turbine but can also influence the velocity recovery downstream of the device.

PENGARUH KEMIRINGAN STRAIGHT BLADE TERHADAP PENINGKATAN KEMAMPUAN SELF-STARTING TURBIN HIDROKINETIK ARTICULATING H-ROTOR

<em>The Articulating of H-Rotor is a development of the turbine from H-Darrieus which has a straight blade tilted with the aim of correcting poor self-starting due to the dominance of lift force. How likely is the influence of straight blade slope on turbine performance and it is important to be examined. The aim of this study was to find out the effect of the straight blade slope of the Articulating H-Rotor turbine to increase the self-starting ability. Hydrokinetic turbine experimental test method was carried out in a water channel (flume) using 3 NACA 0018 profile blades with varying inclination angles of 0<sup>o</sup> (vertical blade), 30<sup>o</sup> (inflated blade) and -30<sup>o</sup> (cupped blade). The result indicated that the Articulating H-Rotor hydrokinetic turbine with a blade slope of 0<sup>o</sup> had a larger RPM value and it was more dominant in working with lift force. The Articulating H-Rotor hydrokinetic turbine with a blade tilted of 30<sup>o</sup> provides higher torque and increases drag, increasing self-starting for rotation. The shape of the turbine frontal area with a blade slope of 30<sup>o</sup> was better able to respond the kinetic energy that raised from the flow velocity distribution profile of the water flow. The results of this study can contribute to the design of the tilted blade H-Darrieus turbine.</em>

Effect of the opening and location ratio on the performance of an H-Darrieus VAWT

Vertical axis wind turbines such as Darrieus turbines are a very interesting category of low wind speed domestic wind turbines. Further research work is needed to enhance their efficiency to fulfill the higher demand in small applications for power generation. The main objective of this work is to find a Darrieus turbine design to boost the starting capacity of the turbine through an opening located at the lower surface of the airfoil. We carried out a thorough CFD (Computational Fluid Dynamics) investigation to determine the impact of the opening position on the Darrieus rotor's output. This new type of airfoil uses a standard NACA 0015 profile and a profile with an opening on the lower surface of the profile. Different sizes of the opening in a symmetrical profile are evaluated through the CFD method to predict the Cp and CT of this H-Darrieus turbine design. Five sections were designed to describe the research of this new H-Darrieus rotor. Generally speaking, the results showed that the Cp decreases with the opening ratio, the desirable rotors with the lower surface opening ratio are 0.12 to 0.36 considering this with the low CpLP.

Numerical study of the effect of turbulence intensity on VAWT performance

This paper demonstrates the capability of CFD to accurately simulate the effect of the flow turbulence intensity on the performance of vertical-axis wind turbines (VAWT). This effect is quite important as it increases the performance of small VAWTs. For this study, two and three dimensional CFD analysis has been performed on different straight-bladed Darrieus-type rotors. Both a small and a large H-Darrieus VAWT with diameters of 0.5 m and 35 m respectively are investigated using NACA0018 blades. Computational results based on a commercial CFD code (Star CCM+) are compared with experimental measurements. Several simulations based on full URANS calculations are proposed. Firstly, the sensitivity of time step, the number of iterations by time step, and discretization schemes are studied. Secondly, the effect of turbulence intensity on the VAWT performance is simulated and compared with experimental data. Finally, results reveal that the power coefficient of a small turbine is increasing for higher turbulence intensity, up to 20%, but stops increasing afterward. For a small turbine H-Darrieus turbine, the power coefficient is increased by 22% when the turbulence intensity is changed from 0.7% to 20%, however, there is no increase detected in the case of a large H-Darrieus wind turbine. The impact of the turbulence intensity was assessed and a range of behaviors was identified.

Numerical Comparison of Two Runners for Gravitational Vortex Turbine

The main purpose of this study is to compare numerically the torque generated by two runners for a gravitational vortex turbine. One of the runners was an H-Darrieus turbine with the rotational flow into the chamber that helped to decrease its negative torque. The other runner was a standard (straight blade) turbine, which determined the performance in both cases. The study was conducted in ANSYSrCFX, where the model was configured at constant operating conditions in both cases. The standard runner performance was higher (75%) than that of the H-Darrieus runner. The highest torque for the standard and the H-Darrieus runners was 0.76 and 0.16 N·m, respectively. The standard runner had a larger fluid contact area than the H-Darrieus runner, which extracted more energy.

Development and Validation of CFD 2D Models for the Simulation of Micro H-Darrieus Turbines Subjected to High Boundary Layer Instabilities

The simulation of very small vertical axis wind turbines is often a complex task due to the very low Reynolds number effects and the strong unsteadiness related to the rotor operation. Moreover, the high boundary layer instabilities, which affect these turbines, strongly limits their efficiency compared to micro horizontal axis wind turbines. However, as the scientific interest toward micro wind turbine power generation is growing for powering small stand-alone devices, Vertical Axis Wind Turbines (VAWTs)might be very suitable for this kind of application as well. Furthermore, micro wind turbines are widely used for wind tunnel testing, as the wind tunnel dimensions are usually quite limited. In order to obtain a better comprehension of the fluid dynamics of such micro rotors, in the present paper the authors demonstrate how to develop an accurate CFD 2D model of a micro H-Darrieus wind turbine, inherently characterized by highly unstable operating conditions. The rotor was tested in the subsonic wind tunnel, owned by the University of Catania, in order to obtain the experimental validation of the numerical model. The modeling methodology was developed by means of an accurate grid and time step sensitivity study and by comparing different approaches for the turbulence closure. The hybrid LES/RANS Delayed Detached Eddy Simulation, coupled to a transition model, demonstrated superior accuracy compared to the most advanced unsteady RANS models. Therefore, the CFD 2D model developed in this work allowed for a thorough insight into the unstable fluid dynamic operating conditions of micro VAWTs, leading the way for the performance improvement of such rotors.

Effect of blade attachments on the performance of an asymmetric blade H-Darrieus turbine at low wind speed

ABSTRACT Wind energy is a significant source of renewable energy and vertical axis wind turbine (VAWT) is one of the advanced wind energy harvesters. Maximum extraction of energy from wind harvesters is a major goal. Researchers are faced with the challenge of enhancing the performance of VAWTs in low wind speed conditions. To this end, researchers have contributed substantially by doing research on the blade design parameters thereby generating innovative and improved VAWT designs. However, there is hardly any work on the performance augmentation of H-Darrieus VAWT with blade attachments on asymmetric blades, which is the main objective of this work. Further, this work investigates the combined effect of turbulence intensity and flow dissimilarity on turbine performance for low wind speed condition. In this paper, blade attachment of length 20 cm (equal to 1/2.5 times blade span) is attached to asymmetric NACA 63–415 blade turbine having fixed blade pitch angle (+5°). NACA 63–415 blade profile is one of the prominent asymmetric series of NACA blades; hence it is considered in this work. The performances of seven different configurations of the turbine with blade attachments have been investigated experimentally at 5.0 m/s and 6.0 m/s using wind tunnel testing. The performance of the VAWT design is systematically improved by changing the number and position of these attachments on the turbine blades. The result shows that both side attachments on turbine blade on its top position have maximum power coefficient (Cp) of 0.13 at tip speed ratio (TSR) 1.8 at wind speed 6.0 m/s among all the turbine configurations tested. There is an improvement of power coefficient by 4.34% when attachments are placed at top of the turbine blade compared to turbine blade without attachment at wind speed 6.0 m/s. Further, maximum power coefficient is increased by 3.28% when turbine is operated from 5.0 m/s to 6.0 m/s for both side attachments at top of the turbine blade. Moreover, due to the combined effect of turbulence intensity and flow dissimilarity, the power coefficient of the turbine configuration having both side attachments has also improved a little. In this case, an improvement of 0.6% in power coefficient of turbine having both side attachments on top of the blade is achieved. As the turbine is a prototype having smaller size hence the effect of turbulence intensity and flow dissimilarity is less, in case of actual turbine of bigger size the effect of turbulence intensity and flow dissimilarity will be more and hence the percentage enhancement of power coefficient will also be more. Hence, it can be concluded that a turbine blade with higher degree of thickness (by using blade attachments) at top portion will increase the performance of an asymmetric blade H-Darrieus VAWT.