Small Horizontal Axis Wind Turbine Research Articles

Consideration of various configurations of SG6043-based rotor applied in small capacity horizontal axis wind turbine

The SG6043 airfoil model is well known for its high aerodynamic efficiency and it is suitable for designing small wind turbine blades. This paper determined the optimal blade configurations using only the SG6043 airfoil model with ten different lengths from 1 m to 10 m. Then, it proposed the most suitable model for a rated wind speed of 5 m/s in Vietnam. The chord and twist values of each blade’s part were optimized by using the Betz optimization method (BOM) in the Qblade open software. Several important characteristic quantities such as lift coefficient (Cl), drag coefficient (Cd), power factor (Cp) and power (P) of the different blade configurations are determined by using a combination of both XFLR5 code and Qblade software. After that, parameters related to operation such as pitch angle and rotation speed of the rotor were also investigated to find the operating conditions for the best efficiency of wind energy exploitation. The obtained results show that the Cp of the blades has a maximum value of about 0.476 and the P has a value of up to 95.319 kW in operating conditions with a wind speed range between 1 m/s and 10 m/s. In addition, the ratios of power to blade surface area (P/S) and the ratios of power to blade volume (P/V) at the wind speed of 5 m/s were also investigated. The results show that rotors with blades ranging from 3 m to 5 m will give much higher P/S and P/V values than other blade configurations under these operating conditions. This emphasizes that these blade configurations will bring more economic benefit because they will consume less material and reduce production time while still ensuring the required capacity value. Finally, the 5 m blade rotor with a capacity of 2.750 kW at a rated wind speed of 5 m/s was proposed as the rotor suitable for individual household use. This design can help millions of Vietnamese households be proactive in their power source, thereby contributing to the significant reduction of CO2 emissions from coal-fired power plants.

Development and Testing of a High Performance Airfoil for Application in Small Horizontal Axis Wind Turbine Blades

Development and Testing of a High Performance Airfoil for Application in Small Horizontal Axis Wind Turbine Blades

Critical issues in the moving reference frame CFD simulation of small horizontal axis wind turbines

Steady computational fluid dynamics with the Moving Reference Frame method has shown promise as a tool for assessing the aerodynamic performance of small horizontal-axis wind turbines, offering sufficient accuracy with low computational costs, thus supporting the development of these machines and facilitating their vital role in the growing distributed energy systems. However, accurately simulating the intricate low Reynolds number flow around the blades of these turbines remains a significant challenge, with certain critical issues yet to be fully resolved. Through a comparative literature review, this study firstly uncovered a lack of standardized simulation settings for small horizontal axis wind turbines, resulting in inconsistencies across different studies. Addressing this gap, the research delves into the critical issues identified, specifically the computational domain cross-section shape and size, discretization scheme accuracy, meshing criteria, freestream turbulence intensity, and turbulence modelling. To rectify these challenges, the study conducts a detailed sensitivity analysis of the aforementioned parameters applied on a well-documented turbine in the literature as a case study. For validation purposes, an empirical method is employed to correct the tunnel wall blockage effect on the case study turbine experimental data. This method is verified, and the correction of the closed test section tunnel data, notably, shows a significant blockage effect, contradicting the notion of insignificance for a blockage ratio of 11.8% in the literature. The analysis revealed how incorrect simulation settings can yield misleading results that initially may align with experimental data but fail to guarantee a reliable numerical setup for extending the study. Ultimately, this research furnishes best practice guidelines for establishing accurate simulation setups.

Optimal airfoil selection for small horizontal axis wind turbine blades: A multi-criteria approach

Over the last century, the growing demand for clean energy has emphasized wind energy as a promising solu-tion to address contemporary energy challenges. Within the realm of wind energy, the wind turbine plays a pivotal role in harnessing the kinetic energy of the wind and converting it into electrical power. Among the various components of the wind turbine system, turbine blades assume a critical role in capturing the wind's kinetic energy and converting it into rotational motion. Consequently, the design of wind turbine blades holds the utmost importance in determining the overall performance and efficiency of the entire wind turbine system. One essential aspect of blade design involves selecting an appropriate airfoil. Throughout history, numerous airfoil profiles have been developed for various applications. Notably, National Advisory Committee for Aeronautics (NACA) and National Renewable Energy Laboratory (NREL) airfoils have been tailored for aircraft and large-scale wind turbine blades, respectively. However, the quest for suitable airfoil types for small-scale wind turbine blades has been ongoing. This study delves into an examination of over 62 distinct NACA and NREL aerofoil types tailored for small horizontal-axis wind turbine blades. Employing specialized software, namely QBlade, specifically designed for modeling and simulating wind turbine blades, the study calculates key parameters such as power output, stress, deformation, and weight for each airfoil. Subsequently, based on the simulated data, the optimal airfoil is identified using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria selection approach. This selection process takes into account simulation results pertaining to power output, stress, deformation, and weight. The decision-making process involving multiple criteria is facilitated using Excel and Python. The findings of this study reveal that among the 62 airfoil types under consideration, the NACA 0024, NACA 2424, and NACA 4424 airfoils emerge as the most suitable choices for small horizontal-axis wind turbine blades.

Comparative Study of the Blade Number and Airfoil Profile Impacts on the Twist/Chord Distribution of a Small Wind Turbine Blade

The blade number and airfoil profile effects on the blade shape of a small horizontal-axis wind turbine (SHWT) were investigated. For this purpose, the NACA4412, SG6042, and SG6043 airfoils, as well as 2, 3, and 4 blades, were considered. Then, two optimization processes were used: first, the blades were designed to maximize the power coefficient ( C p ), and then a multiobjective optimization that included both maximizing C p and maximizing the starting torque ( Q s ) was employed. The differential evolution (DE) algorithm was employed to perform the optimization, and the blade element momentum aerodynamic approach was used to conduct the relevant computations. Also, to ensure the performance of the optimal blades, the computational fluid dynamics method was employed as well. The findings revealed that regardless of the number of blades and the type of airfoil, raising the twist angle ( θ p ) and chord length ( c ) along the radial direction of the blade, especially at the root part, helps increase the Q s . It was observed that increasing the number of blades does not have a significant effect on the θ p distribution of the selected airfoils, but the c of the blades fitted with all three airfoils decreases. Regardless of the number of blades, while the geometry of blades utilizing the NACA4412 and SG6042 airfoils are close to each other, the blade with the SG6043 airfoil has the shortest c , which reduces the generated Q s of blades fitted with this airfoil. The results also establish that by increasing the number of blades from 2 to 3, the power coefficient ( C p ) of the blades fitted with all three airfoils increases, but by further increasing the number of blades from 3 to 4, the change in C p completely depends on the airfoil profile.

Techno-economic analysis and optimization of hybrid energy systems based on hydrogen storage for sustainable energy utilization by a biological-inspired optimization algorithm

Wind energy resources based on hydrogen energy storage systems are recognized as clean alternative sources from the perspective of sustainable development. A low-cost hydrogen energy storage system is recognized as a cornerstone of a renewables-hydrogen economy. The hybridization of wind turbines, as a non-dispatchable resource, and hydrogen storage system, as energy storage, can provide a promising hybrid energy system. The main outlook of the present paper is to develop a biological-inspired optimization algorithm for the optimal design of an off-grid wind power generator considering a hydrogen energy storage system. The parameters of the system are optimized with respect to two objective functions, namely the total cost, and load loss of the system. To obtain an efficient optimum capability, an artificial bee colony optimization method is introduced. Its results are compared with the results of the particle swarm optimization algorithm. Eight different small horizontal-axis wind turbines are used for the optimal design of an off-grid system. A sensitivity analysis is conducted by varying the capital cost of the components to determine how total cost and load loss are affected by the change of the input variables. Simulation results show that at load loss = 0 and 20 %, the cost of energy (COE) is around 0.6907 and 0.3771 $/kWh, respectively. The variation of wind turbine (WT) and hydrogen storage system capital costs have a significant impact on total cost value. Among the investigated systems, the Fortis-WT- hydrogen storage system with 0.5987 $/kWh COE has the minimum cost and maximum reliability (100 %). The superiority of the proposed algorithm compared to the particle swarm optimization algorithm is confirmed.

A Modeling Study Focused on Improving the Aerodynamic Performance of a Small Horizontal Axis Wind Turbine

The excessive burning of the fossil fuels has excessively changed the global temperature in the last few decades. The global warming caused due to the burning of the fossil fuels has initiated a need of increasing the use of renewal energy sources. The wind energy is one of the renewable energy sources that can mitigate the excessive global dependency on the fossil fuels. For locations with low-to-medium wind speeds (less than 7 m/s), the main problem is with the starting of the wind turbine. To start a stationary wind turbine, not only is it necessary to overcome the inertia and static friction of the turbine, but the angle of incidence of the wind relative to blade profile also needs to be favorable. Thus, at low wind speeds, the resulting low torque is not enough to start the turbine. It is, therefore, necessary to incorporate a good starting torque in the design requirements of turbines. In this paper, a modeling study is performed using the Pro/E, ADAMS and MATLAB software to improve the starting behavior of a horizontal axis wind turbine for the Cherat location in the northern areas of Pakistan. The yearly average wind speed in the northern areas of Pakistan is less than 5 m/s. The blade element momentum (BEM) theory is used to calculate the optimized wind turbine blade parameters (blade angles and chord lengths) that correspond to the maximum starting torque. Based on the optimized wind turbine blade parameters, Pro/E models were developed and imported to ADAMS software to calculate the torque. As compared to the initial wind turbine model, for the optimized wind turbine model, the starting torque increased from 22.5 N-m to 28 N-m and the coefficient of performance (COP) increased from 0.42 to 0.49 at a tip–speed ratio of 4. The starting torque of the wind turbine should exceed the resistive torques due to bearing friction, generator static, dynamic torque and the inertia of the rotor in order to start the wind turbine. The starting behavior of the horizontal axis wind turbine was successfully improved, and the optimized wind turbine model showed an increased starting torque for low-to-medium wind speed ranges.

Aerodynamic Performance Investigation of a Small Horizontal Axis Wind Turbine with Multi-Airfoil Blade Profiles of SD2030 and E231 Using Wind Tunnel Experiments and BEM Theory Method

The goal of this study is to investigate the performance of a small horizontal axis wind turbine blade at wind speeds of lower than 5 m/sec numerically and experimentally. The rotor blade has a diameter of 0.7m and consists of two airfoils profile: the thin airfoil SD2030 selected at the outboard region, and the thick airfoil E231 at the inboard region. The former airfoil, SD2030, is highly recognized for aerodynamic performance as it is suitable for low Reynolds number (Re), while the latter airfoil E231 is likewise appropriate for low Re flow but has a higher thickness-to-chord ratio which acts as structural support and good strength at the hub. The selected airfoils were analyzed using QBlade software based on XFOIL and Blade Element Theory (BEM) for different Reynolds number. Using a low-speed wind tunnel and Reynolds number ranging from 1x105 to 5x105, experiments at pitch angles of 5ο were conducted to determine the variation in torque and predict blade performance. The results reveal that the turbine with two hybrid different airfoil profiles have achieved a better start-up response at low wind speed of 1.5 m/s and a high-power coefficient of 0.34 with 3.7 tip speed ratio. The turbine can be used to generate a power of 0.5W at 1.5 m/s and a maximum power harvest of up to 20W at a wind speed of 7m/sec. The turbine's performance compared to other small wind turbines from the literatures demonstrate good performance and the results obtained from wind tunnel data were found in satisfactory agreement with the results provided by the BEM code.

Optimization of Small Horizontal Axis Wind Turbines Based on Aerodynamic, Steady-State, and Dynamic Analyses

In this article, the model of a 5 kW small wind turbine blade is developed and improved. Emphasis has been placed on improving the blade’s efficiency and aerodynamics and selecting the most optimal material for the wind blade. The QBlade software was used to enhance the chord and twist. Also, a new finite element model was developed using the ANSYS software to analyze the structure and modal problems of the wind blade. The results presented the wind blade’s von Mises stresses and deformations using three different materials (Carbon/epoxy, E-Glass/epoxy, and braided composite). The modal analysis results presented the natural frequencies and mode shapes for each material. It was found, based on the results, that the maximum deflections of E-glass, braided composite and carbon fiber were 46.46 mm, 33.54 mm, and 18.29 mm, respectively.

NACA2412 airfoil based method for design and aerodynamic analysis of small HAWT using modified BEM approach

Efficient utilization of wind energy depends on careful selection and suitable design of Wind Turbine (WT) blades. Small scale Wind Turbines (SWT) normally operate in the low range of Angle of Attack (AoA). This makes the task even more difficult for designing and optimization of WT blades. This article deals with an airfoil based computational approach to design the blade for a standalone small scale Horizontal Axis Wind Turbine (HAWT). A procedure has been proposed to find the important parameters and analyze the performance characteristics for a three bladed HAWT operating under the wake rotation. Computational code has been written to find optimum blade profile. Twist angle variation, chord length and other related parameters are determined with the help of program. Comparison between different types of airfoil has been made to figure out the most suitable one. Airfoil selection and design approach are intended to make Wind Turbine blade efficient specially under low range of AoA. Characteristics of the Wind Turbine obtained analytically from this procedure are compared with several other reported earlier in some of the literatures. The result obtained by the proposed procedure is simpler and more efficient than BEM theory – a method normally employed for blade design.

Analysis on aerodynamic performance of mine horizontal axis wind turbine with air duct based on breeze power generation

Developing wireless sensor networks based on breeze power generation is of great significance to promote the development of intelligent mines. In this paper, a small horizontal axis wind turbine with air duct was designed for the underground environment of coal mine. The aerodynamic performance of the wind turbine was analyzed by constructing a three-dimensional solid model of the wind turbine. The results show that under the condition of low wind speed underground, the air flow entering the air duct in the outer basin is accelerated and rectified, and the velocity near the impeller increases. The pressure value at the front end of the blade is the largest and the pressure value at the rear end of the blade is the smallest. A certain range of negative pressure zone is formed at the rear end of the impeller, which is conducive to the operation of the wind turbine. After the air flow passes through the impeller, the speed decreases and the speed is the lowest near the rotating shaft of the impeller. Inner basin: the air flow velocity increases gradually along the radial direction of the impeller centre. The pressure at the front end of the blade is greater than the atmospheric pressure, which is conducive to promoting the stability and sustainability of the wind flow and facilitating the operation of the wind turbine. When the wind speed reaches the rated wind speed of the wind turbine, the power, torque and output power of the wind turbine increase, which can provide effective power generation. Compared with other aerofoils, NACA5505 air foil has higher lift drag ratio and thrust coefficient, and is more suitable for downhole low wind environment. Compared with the wind turbine without air duct, the wind turbine with air duct has higher wind energy conversion and output power at low Reynolds number, which verifies the feasibility of the wind turbine with air duct. In the case of low incoming wind speed and no expansion of the size of the wind turbine, improve the output power of the wind turbine and meet the intrinsic safety requirements of the wind turbine. The research can provide technical support for the continuous power supply of wireless intelligent sensors in the mine environment, and provide scientific basis for mine safety production and fine management, which has long-term economic and social benefits.

Experimental and Numerical Investigation of the Effect of Blades Number on the Dynamic Response of a Small Horizontal-Axis Wind Turbine

The new energy scenario is rising a strong interest towards the distributed production from renewable sources; among them, wind seems to be one of the most interesting and at the same time critical due to the challenges of the conversion technology. Operation of small wind energy conversion systems is generally very complex due the extremely variable regime of operation and the high turbulent wind, so that a deep knowledge of the dynamic response of such devices is crucial not only for optimising their performances but also to make them comfortable to be used in residential areas. For these reasons, the present work is focused on analysing the effect in changing the number of blades on a small horizontal axis wind turbine through an experimental campaign in the wind tunnel. The turbine dynamics has been characterised running some “wind ramp” tests and analysing the rotor capability in following the wind as well the vibrations transmitted by the turbine during the operation. Results demonstrate that a higher number of blades, despite a small decrease of performance, can make the machine more efficient in operating at low wind regimes. At the same time, a higher number of blades can make the rotor efficient even at lower speed of rotation, thus limiting the risks of having high magnitude vibrations.

Effects of blade number on the aerodynamic performance and wake characteristics of a small horizontal-axis wind turbine

Small-scale horizontal-axis wind turbines (SHAWTs) are powerful equipments for wind energy conversion. Furthermore, the wake vortices generated by SHAWTs are used in structural engineering to potentially mitigate vibrations. The blade number of SHAWTs is an important parameter for determining the wake vortices, and thus, in addition to its impact on power generation, it significantly influences structural vibration control. Consequently, the aerodynamic performance and wake characteristics of SHAWTs, with blade numbers from 2 to 5 and tip speed ratio from 1 to 6, were systematically investigated using large-eddy simulations and wind tunnel tests. A superior SHAWT with a high power coefficient (>35 %) was designed. The near-wake characteristics and wake evolution were highly sensitive to blade number. An increased number of rotor blades resulted in a (i) wider near wake, (ii) faster decrease in streamwise vorticity, and (iii) greater velocity deficit (VD) and turbulence intensity (TI) in the near wake. Furthermore, in the far wake, the unstable positions of the tip vortices and peak positions of the TI were closer to the rotor and the VD recovered faster, causing the wind-speed distribution to transition from W-shaped to V-shaped. The results have significant implications for the design optimisation of wind energy harvesting. Moreover, they are potentially beneficial for the control of structural vibration using SHAWTs.

An Investigation of Design and Simulation of Horizontal Axis Wind Turbine Using QBlade

Abstract The wind turbine blade design is important in obtaining an effective wind turbine. In the field of wind energy, it is essential to understand the design and parameters affecting the blades of the wind turbine in order to obtain a successful design. However, most of the parameters are dependent on each other and this makes the design of wind turbines a challenging task. This research paper used the QBlade software to analyze and optimize the behavior of the small horizontal axis wind turbine. The software applies the Blade Element Momentum Theory (BEM) to study the wind turbine blades by calculating the drag and lift coefficients which were achieved by dividing the blades into 10 ascending segments. The twist angle and chord length of the blade are optimized to get the highest performance. Among the various airfoil types, the SG-6041 airfoil type was selected to build the blade structure. The calculated power coefficient was almost 0.4, which is considered high given that it was calculated under 10 m/s average wind speed and 1-meter length blade conditions. Where all the results are logical and reasonable, the software is proven to be reliable. The paper also evaluates the wind characteristics in different locations in Iraq in order to find the most optimal promising locations in Iraq.

Experimental study of turbulence intensity on the wake characteristics of a horizontal-axis wind turbine

ABSTRACT A time-resolved particle image velocity (TR-PIV) system was used to test the wake flow of a small horizontal-axis wind turbine at tip speed ratios (TSRs) in the range of 4–6 under uniform inflow and turbulent inflow in order to study the impact of turbulence intensity on wind turbine wake characteristics. The impact of incoming turbulence on the wake structure of a wind turbine and its mechanism was examined by comparing and analyzing the turbulence properties of the wake flow, including velocity field, vortex structure, additional turbulence intensity, and energy distribution coefficient. It was found that tip vortex structure remained intact in the range of 9 R under uniform inflow, and the longitudinal distribution of turbulent intensity had double peaks, indicating that it was in the near wake zone. Under turbulent inflow, the three vortex systems could not be distinguished at the position of 5 R, and the longitudinal distribution of turbulent intensity did not have peaks, the wake vortex system was broken and the wake transitioned to the far wake zone. With the increase in the turbulence intensity and tip speed ratio, the contribution of the longitudinal component of turbulence intensity to the turbulent kinetic energy increases, which is also the reason for the rapid wake recovery. Additionally, the recovery of the wake velocity was sped up in the range of 3 R and gradually decreased after 3 R.

Multi-Objective Optimization of a Small Horizontal-Axis Wind Turbine Blade for Generating the Maximum Startup Torque at Low Wind Speeds

Generating a high startup torque is a critical factor for the application of small wind turbines in regions with low wind speed. In the present study, the blades of a small wind turbine were designed and optimized to maximize the output power and startup torque. For this purpose, the chord length and the twist angle were considered as design variables, and a multi-objective optimization study was used to assess the optimal blade geometry. The blade element momentum (BEM) technique was used to calculate the design goals and the genetic algorithm was utilized to perform the optimization. The BEM method and the optimization tools were verified with wind tunnel test results of the base turbine and Schmitz equations, respectively. The results showed that from the aerodynamic viewpoint, the blade of a small wind turbine can be divided into two sections: r/R < 0.52, which is responsible for generating the startup torque, and r/R ≥ 0.52, where most of the turbine power is generated. By increasing the chord length and twist angle (especially chord length) in the r/R < 0.52 section and following the ideal chord length and twist angle distributions in the r/R ≥ 0.52 part, a 140% rise in the startup torque of the designed blade was observed with only a 1.5% reduction in power coefficient, compared with the base blade. Thereby, the startup wind speed was reduced from 6 m/s for the base blade to 4 m/s for the designed blade, which provides greater possibilities for the operation of this turbine in areas with lower wind speeds.

Harvesting air energy from extractors with a small horizontal axis turbine

In greenhouses and other agricultural facilities, air extractors are used for air renewal and control of environmental conditions. The electrical energy delivered to the extractor is converted into the energy of the exhaust air and is lost in the atmosphere. The objective of this work was to test a small horizontal axis wind turbine (SHWT) installed in front of an axial extractor and to present the energy balance of the extractor-wind turbine assembly. This was done for four different treatments: extractor alone, extractor with cone, extractor with a wind turbine, and extractor with cone and a wind turbine. A statistical analysis was performed, obtaining means and standard deviations. The energy balance analysis showed that with the designed device, built including a cone and a SHWT and installed at the outlet of the extractor, it is possible to harvest up to 50% of the wind energy that leaves the extractor and is lost in the atmosphere.

Electrical design of a smart control and monitoring system for small horizontal-axis wind turbines

The popularity of small wind turbines would rise in future, because of electricity prices are still growing. Next generation of small wind-turbines can have higher efficiency values. Under wind gusts and turbulences, the system should be very sensitive to wind conditions. In this work, it is presented a control system that can improve the performance of commercial small-scale wind turbines by including active pitch and load control. We show the electrical design of a smart active pitch control to increase the energy generation of micro-wind turbines (< 5 kWp). The electrical design controls a simple mechanism that allows the rotation of the blades by using an actuator that moves the blades according to the energy desired. The load control is also shown. These two control strategies maximise the power output at all wind conditions, and can increase the performance of small wind turbines. Moreover, important signals that allow safety actions and feedback data are monitored. The electro-mechanical design is robust and economical compare to the traditional hydraulic solution, which will increase its potential adoptability by users.

Multi-Objective Optimization and Optimal Airfoil Blade Selection for a Small Horizontal-Axis Wind Turbine (HAWT) for Application in Regions with Various Wind Potential

The type of airfoil with small wind turbine blades should be selected based on the wind potential of the area in which the turbine is used. In this study, 10 low Reynolds number airfoils, namely, BW-3, E387, FX 63-137, S822, S834, SD7062, SG6040, SG6043, SG6051, and USNPS4, were selected and their performance was evaluated in a 1 kW wind turbine in terms of the power coefficient and also the startup time, by performing a multi-objective optimization study. The blade element momentum technique was utilized to perform the calculations of the power coefficient and startup time and the differential evolution algorithm was employed to carry out the optimization. The results reveal that the type of airfoil used in the turbine blade, aside from the aerodynamic performance, completely affects the turbine startup performance. The SG6043 airfoil has the highest power coefficient and the BW-3 airfoil presents the shortest startup time. The high lift-to-drag ratio of the SG6043 airfoil and the low inertia of the turbine blades fitted with the BW-3 airfoil make them suitable for operation in windy regions and areas with low wind speeds, respectively.

Mechanism study of flow characteristics on small HAWT blade surfaces based on airfoil concavity under yaw conditions

Aiming to solve the power output reduction caused by the flow separation, this study applied a passive flow control method on blade suction surfaces of a small horizontal axis wind turbine. An airfoil with a semi-elliptical concavity was introduced, and several concave blades were, thus, designed. Among them, the blade with a concavity located at 80% chord and a length of 350 mm was selected for further analysis according to the aerodynamic performance. As a result, it has been found that the concave airfoil had better performance at high wind speeds, low rotational speeds, and small yaw angles, especially the positive yaw conditions. The flow field mechanism could be interpreted with a positive pressure gradient generated by the airfoil concavity. Under the positive yaw angle of 10°, the concavity effect resulted in a greater aerodynamic lift. The azimuth angle of 0° shows an obvious control effect at the blade tip. On the contrary, the concavity has little effect at an azimuth angle of 120° near the leading-edge. At the azimuth angle of 240°, a significant concavity effect at the blade root could be found, while the aerodynamic benefits were not as remarkable as an azimuth angle of 0° in the vicinity of the blade tip. Aside from that, when the flow separation was serious due to the three-dimensional rotational effect, the concavity has no distinct effect on separation control. In essence, the airfoil concavity had a favorable impact on flow separation control and effectively enhanced the power output of the wind turbine.