Designing, Optimizing, and Manufacturing of Horizontal Wind Turbine Blades Using the Available Resources

Yhya Abdullah Al-Wazer Depertment of machenical engineering General Corporation for Electrical Industries & Renewable Energy Sanaa, Yemen abdullahyhya141@gmail.com Gamil Abdullah Al-Sharif Depertment of machenical engineering General Corporation for Electrical Industries & Renewable Energy Sanaa, Yemen mely104haja@gmail.com

Abstract—The research aims to enhance wind turbine blade performance by utilizing available technologies and considering constraints such as limited resources. The focus is on developing blade designs that optimize material use, manufacturing techniques, and performance while reducing costs. Alternative and cost-effective materials are considered for blade manufacturing. Analytical models and computational simulations are deployed to validate the initial design and analyze multiple parameters. Simulations and mold production are conducted before manufacturing the blades. Assembly, installation, and testing processes evaluate blade performance.
Keywords— Aerodynamics, Blade design, Blade manufacturing, Blade optimization, Performance improvement, Simulation, Wind turbine blades Introduction The urgency to transition to renewable energy sources has grown substantially over recent decades, driven by environmental concerns and the need for sustainable power solutions. As global efforts to combat climate change intensify, renewable energy sources such as wind power are becoming increasingly crucial. Wind energy, in particular, offers a promising pathway to reduce carbon emissions and dependence on fossil fuels. Since 1973, small-scale wind generators have gained traction in residential and farming sectors, especially in off-grid regions [1][2]. However, the efficiency of wind turbines hinges on blade design, optimization, and manufacturing [3][4] [5]. While most turbine components are recyclable, blades pose challenges due to energy-intensive disposal methods. Current wind turbine technology often relies on advanced materials and manufacturing processes that are not feasible in resource-limited regions. The high costs, specialized equipment, and skilled labor required for producing high-quality blades create significant barriers to adoption [6][7][8]. Existing research highlights several advancements in cost-effective blade design and materials, such as the use of natural fibers and composites [9][10]. Simplified manufacturing techniques, including modular blade designs and 3D printing, also show promise in reducing production complexity and costs [10][11]. Despite these advancements, a specific gap exists in developing approaches that utilize locally available resources and simplified manufacturing processes. This research addresses this gap by proposing methods to optimize blade performance using accessible technologies and materials. Previous research and available sources will be reviewed to identify commonly used and effective designs. Once the optimized design is identified, attention will shift to selecting affordable and accessible materials for blade manufacturing. The manufacturing process will be examined, using easily accessible tools, equipment, and techniques like cutting, shaping, and assembly with basic hand tools. This research aims to explore cost-effective design, optimization, and manufacturing of wind turbine blades using accessible resources and techniques, potentially advancing wind technology and renewable energy adoption. Background and Problem Horizontal-axis wind turbines are vital for renewable energy but face challenges in costly and technologically sophisticated blade enhancement, hindering adoption in resource-limited regions. These challenges include: Lack of advanced manufacturing technologies required for wind turbine blade production, such as 5-axis CNC machines and other specialized equipment. Limited expertise and experience in the manufacturing of wind turbine blades. Shortage of skilled labor capable of producing high-quality wind turbine blades. Insufficient availability of required raw materials, such as carbon fiber, for the manufacturing process. High costs associated with the materials and processing required for wind turbine blade production. Limited number of established wind energy projects and lack of widespread awareness about the importance of wind turbine technology for power generation. Hampering advanced designs and access to resources. Addressing these constraints can lead to more efficient designs and cost reduction, making wind turbine technology more accessible in resource-limited regions Research Gap While previous studies have made significant strides, they often rely on advanced technologies and materials that may not be available in resource-limited regions. This research aims to bridge this gap by focusing on the use of readily available resources and simplified manufacturing techniques to enhance wind turbine blade performance. Objectives and Significance The objective is to enhance blade performance using available technologies, alternative materials, and simplified manufacturing techniques. By understanding the wind turbine blade design process, it is possible to manufacture high-performance blades with accessible resources. This research can drive technological advancements, promote affordable renewable energy, and stimulate innovation in wind turbine blade technology. Literature Review Wind Turbines Wind turbines are integral to sustainable construction, particularly in urban settings [12]. They are categorized based on various factors such as configuration, capacity, and installation location [13]. Classification of Wind Turbines Wind turbines are broadly classified as horizontal-axis or vertical-axis, with the former being more prevalent due to their efficiency and cost-effectiveness [13]. Additionally, turbines can be categorized as upwind or downwind, each presenting unique operational considerations [13]. Small Wind Turbines Small wind turbines, typically with rotor areas less than 200 square meters, find utility in low to moderate wind speed areas near energy demand centers [14]. Design considerations include blade geometry, material selection, and aerodynamic performance [15] [16]. Aerodynamic Principles of Turbines Blade Sweep Area: Describes how increasing blade length enlarges the swept area, impacting energy values. Blade Sweep Area is shown in Fig. 1.

Depiction of the Sweeping Area. [17] Wind Energy Parameters: Introduces the energy coefficient (C_p) for turbine efficiency, typically ranging from 30% to 45%, with reference to the Lanchester—Betz Limit [17] [18] [13]. Lanchester—Betz Limit: Sets the maximum turbine efficiency at 59.26%, influenced by the axial induction factor (a), which peaks at 16/27 when the factor a is 1/3 [13] [19]. a = axial induction factor (the fractional decrease in wind velocity between the free stream and the rotor plane). Speed Ratio Maximum: Highlights the importance of speed ratio (λ) in turbine design typically ranging from 6 to 9 for 3 bladed turbines [20]. In Fig.2 you can see the variations in the blade design with respect to the variation of the maximum speed ratio. Blade Geometry: plays a crucial role in turbine performance, with variations in shape and aerodynamic profile impacting efficiency and power generation [21] [22]. Analysis of Aerodynamic and Aeroelastic Characteristics of Wind Turbines The behavior of wind turbines is influenced by aerodynamic principles, often simplified in theoretical frameworks. Models like the classic Blade Element Momentum (BEM) method are used for evaluating power coefficients, involving computational simulations [17]. Theoretical Framework for Aerodynamic Behavior A simplified one-dimensional concept is often applied to wind turbine aerodynamics, neglecting friction and rotational speed components [17]. Equations derived from conservation principles provide insights into power generation and drag force [17]. The power coefficient, critical for turbine design, reaches its maximum at the Betz limit [17]. Conventional Blade Element Moment Theory Analyzing wind turbine blade behavior is complex, involving particle interactions and load determination for each element [18]. Equations describe the drag and torque forces on the blade, with coefficients derived from literature [18]. The Prandtl correction factor is utilized to account for tangential forces [18]. Composite Materials Wind turbine blades require careful manufacturing to meet operational demands, with various methods like pre-impregnated materials and resin infusion employed [23]. Laminate composites and sandwich compounds are common in modern turbines, with material selection guided by composite mechanics knowledge [13]. Reinforcements Composite materials rely on natural or non-natural fibers for reinforcement, with glass fibers and carbon fibers being predominant choices [24]. The properties of these fibers dictate their suitability for different blade requirements [24]. Natural Fibers Natural fibers offer an eco-friendly alternative, though with lower mechanical properties compared to glass or carbon fibers [3][25]. Despite this, they find utility in certain applications due to their specific characteristics [25].

Displays the ratios of maximum speeds in relation to the number of blades [20]

Previous Studies and Related Research Existing research highlights several advancements in cost-effective blade design and materials. Studies have investigated the use of alternative materials such as natural fibers and composites, which balance cost and performance [6][7][8]. Additionally, research on simplified manufacturing techniques, such as modular blade designs and the use of 3D printing, has shown promise in reducing production complexity and costs [9][10][11]. Research has explored the utilization of natural fibers in turbine blade construction, including bamboo-based compounds and novel fibers like Stipa Obtusa [3][25][26][27]. Studies across various domains have demonstrated the benefits of optimal blade designs, composite material utilization, and innovative manufacturing techniques [28][29][30][31]. Methodology The methodology encompasses verifying the initial design through analytical models and computational simulations to ensure fluid behavior and aerodynamics are considered. Design simplicity and performance efficiency are prioritized, with various parameters analyzed for validation. After design and analysis, simulations of the blades and molds precede manufacturing, followed by assembly, installation, and testing processes. Conceptual Design of the 5kW Blade Wind Velocity The wind velocity is crucial in determining energy potential, with data obtained from the Wind Atlas for the Republic of Yemen. A wind speed of 8m/s (TABLE I.), typical in Al Hudaydah Governorate, serves as the basis for design considerations. Geometric Parameters The 3-blade configuration adheres to industry standards, with a sweeping area compatible with small wind turbines [27][26]. Initial design parameters are summarized in TABLE (II). Choosing the Optimal Profile for Aerodynamic and Structural Performance The selection of the optimal profile involves a comprehensive analysis considering aerodynamic performance, structural stability, weight, durability, manufacturing, assembly, and economic factors. The Computational Fluid Dynamics (CFD) simulations play a critical role in this analysis by assessing parameters such as lift-to-drag ratio, pressure distribution, and turbulence effects around the blade surface. Specific parameters considered in the CFD simulations include Reynolds number, angle of attack, and flow separation points [32][33][34]. Simulation and Analysis of the Rotating Blade Aerodynamic Dynamic Simulation Processes Simulation processes ensure the blade design achieves its intended purpose, focusing on streamlined shape and aerodynamic efficiency. Structural Blade Design/Model Analysis Blade structure and materials, whether hollow or solid, plate thickness, and material properties are defined to determine weight and corresponding frequencies for different speeds. The simulations models consider both static and dynamic loads to ensure the blade can withstand operational stresses without permanent deformation. Static Blade Loads and Deflection Structural design verification includes withstanding static loads and stresses at various speeds without permanent deformation. This involves calculating the maximum deflection and stress distribution using analytical models and validating them with simulations.

TABLE I. THE ANNUAL AVERAGE WIND SPEED IN SEVERAL YEMENI GOVERNORATES AT A HEIGHT OF 10M. Ranking Station 10 m above ground E N Estimated Elevation [m.a.s.l] Mean Wind velocity [m/s] 1 Hodeidah (CAMA/WMO) 45o 02’ 12° 50’ 12 9.2 / 7.0 2 Taiz 44o 08’ 13° 41’ 1385 6.6 3 Aden (CAMA/WMO) 45o 02’ 12° 50’ 3 6.5 / 7.2 4 Sana’a 44o 11’ 15° 31’ 2190 3.7 5 Ibb 44o 20’ 14° 00’ 1929 1.5

TABLE II. THE VALUES OF THE INITIAL DESIGN PARAMETERS Parameter Unit Value Power KW 5 Velocity m/s 8 Cp 0.45 ρ kg/m^3 1.2

Modeling Blades and their Manufacturing Mold Blades and molds are modeled using three-dimensional software, with attention to segmentation for manufacturing ease. Mold design is verified before producing the final blade model, ensuring accuracy and quality. Manufacturing considerations include the use of fiberglass composites and CNC machining, with specific focus on the challenges in resource-limited settings such as availability of skilled labor and advanced equipment [35][36][37]. Manufacturing Considerations Materials and Processes: The manufacturing process involves selecting locally available materials, such as fiberglass, which balances cost and performance. The process includes cutting, layering, and curing the fiberglass to form the blade structure. Potential challenges include limited access to high-quality raw materials and advanced manufacturing equipment like 5-axis CNC machines. The manufacturing process will be examined, using easily accessible tools, equipment, and techniques like cutting, shaping, and assembly with basic hand tools. Labor and Expertise: The shortage of skilled labor is addressed by simplifying the complexity of blade and manufacturing process. This ensures that high-quality blades can be produced despite limited expertise and experience in the region. Testing and Validation The testing phase includes both laboratory and field tests to measure specific performance metrics such as power output, efficiency, structural integrity, torque, and rotational speed under operational conditions. Initial observations are compared to design goals, and iterative improvements are made based on test results. Computational simulation results Choosing the Optimal Profile for Aerodynamic and Structural Performance Upon determining the Reynolds number, various airfoil surface models were considered, including S809, NACA4412, S823, S822, among others as shown in Fig. 3. The QBlade program was used for the comparison between these surfaces to choose the suitable model. After comparing these surfaces, S822 was selected because it achieved a maximum Cp coefficient of up to 0.425 under design conditions and at a blade tip speed ratio of 7. The other airfoil surface that performed closely to S822 was NACA4412 at a blade tip speed ratio of 10. However, in general, S-Series surfaces are commonly used in small wind turbine blades because they provide greater blade stiffness. Aerodynamic Analysis with BEM Using the Blade Element Momentum (BEM) methodology, tangential and axial induction coefficients were determined to signify the energy extracted from the air for blade motion also the simulation results for the airfoil shape of the blade was obtained as shown in Fig 4. Through 1058 iterations, values for these results were obtained.

Cp values for each type of tested airfoil surface Blade Structure and Material Analysis Results The blade structure, identified as hollow with varying thicknesses, was analyzed along with material properties for cavity filling. Blade weight and corresponding frequencies for rotational speeds were established. Static Blade Load and Deflection Analysis Result Loads acting on each part of the blade at different wind speeds were defined to ascertain stresses, pressures, and deflection as shown in Fig 5. These loads and forces were based on previously obtained results.

Simulation Using Computational Fluid Dynamics (CFD) Software After BEM simulation, blade modeling in SOLIDWORKS preceded CFD simulation in ANSYS. A computational domain representing the fluid medium, air, was defined along with boundary conditions and parameters using the CFX tool as shown in Fig. 6. Simulations were conducted for various wind speeds and rotational velocities, with torque results compared to prior analyses and ANSYS software as shown in Fig. 7 and TABLE III.

The simulation results for the airfoil shape of the blade

Displays the corresponding results for the loads acting on each part of the blade at a wind speed of 11 m/s and a thickness of 0.5 cm

CFX tool to define boundary conditions and other parameters TABLE III. TABLE OF RESULTS wind speed [m/s] Angular Velocity [radian/s] Torque from QBlade [N m] Torque from ANSYS [N m] 3 5.828571 46.5422199 46.1755 4 7.771428571 82.74172426 84.4061 4.5 8.742857143 104.7199948 104.531 5 9.714285714 129.2839442 128.215 5.5 10.68571429 156.4335724 154.24 6 11.65714286 186.1688796 184.934 6.5 12.62857143 218.4898656 216.262 7 13.6 253.3965306 250.723 7.5 14.57142857 290.8888744 287.238 8 15.5429 330.9668971 324.573 8.5 16.51428571 373.6305986 367.927 9 17.48571429 418.8799791 411.976 9.5 18.45714286 466.7150384 458.389 10 19.42857143 517.1357767 507.375 12 23.31428571 744.6755184 728.597

Torque results compared for various wind speeds and rotational velocities.

The torque results from QBlade and ANSYS show strong correlation, indicating the reliability of the simulation models. These results validate the aerodynamic efficiency and structural integrity of the S822 airfoil, which is critical for achieving cost-effective and high-performance wind turbine blades Three-dimensional Modeling and Manufacturing Creating a three-dimensional model for the blades and designing their specific mold Following the simulation process, the blade was modeled in SOLIDWORKS using data from the QBlade program. Additionally, a mold for the blades, consisting of two sections to accommodate the irregular blade shape, was designed as shown in Fig. 8.

The mold, blades, and Hub in SOLIDWORKS. Mold Manufacturing The mold, crafted using a three-axis CNC machine, underwent a two-stage manufacturing process involving part production and assembly as shown in Fig. 9.

The mold for the blades after it has been prepared. Blade Manufacturing Blade production commenced with layering and laminating fiberglass on each mold part, followed by joining the segments to form complete turbine blades. Subsequent processes included foam filling, emery, sanding, and final touches, resulting in accurately constructed blades as shown in Fig. 10. Assembly, Installation, and Testing Assembly: All components were assembled together in preparation for installation as shown in Fig. 11. The components specifications shown in TABLE IV. Installation: An initial 4-meter tower was constructed for preliminary testing as shown in Fig. 12 before mounting the blades on the 20-meter turbine tower. Testing: After installing the blades on the test tower, it was observed that the blades rotate at low wind speeds and exhibit good and stable performance in terms of balance between the blades. However, in order to conduct accurate tests and obtain precise values, specialized devices are required to measure and determine wind speed, direction, and rotational speed. Unfortunately, these devices were not available to us due to financial constraints. Cost Analysis A cost comparison was conducted to evaluate the economic feasibility of the proposed wind turbine blade design. Key cost components include: Materials: Fiberglass was chosen for its cost-effectiveness and durability, significantly reducing material costs compared to carbon fiber. Manufacturing: Simplified manufacturing techniques were employed, minimizing the need for advanced machinery and skilled labor. Overall Cost: The total cost of producing a 3.5 m wind turbine blade using the proposed methods is estimated to be 40% lower than traditional methods, making it more accessible for resource-limited regions. Cost Components Ccarbon as the cost of carbon fiber with fiberglass per blade, Cfiberglass as the cost of fiberglass per blade,Mtraditional as the manufacturing cost using traditional methods,M(simplif¯ι ed) as the manufacturing cost using simplified methods. Traditional Total Cost: Ttraditional=Ccarbon+Mtraditional Proposed Total Cost: Tproposed=C(f¯ι berglass)+M(simplif¯ι ed) Ccarbon =$ 500 , Cfiberglass=$ 300, Mtraditional=$1000, M(simplif¯ι ed)=$ 600 Ttraditional=$ 1500, Tproposed=$ 900 Savings Percentage =(1-Tproposed/Ttraditional )×100%=(1-900/1500)×100% Savings Percentage =(1-0.6)×100%=40 %

Final shape of the blades and hub after completing the manufacturing process.

Assembly of components TABLE IV COMPONENTS SPECIFICATIONS Compound Specifications Blades Length: 3.5 m, Material: fiberglass Hub Material: cast iron Test Tower Heigh: 4m, Material: cast iron Shaft Dia: 50 mm ,Material: cast iron Gear box Not used Generator Not used

The blades after being installed on the test tower Discussion, Conclusions, and Future Work Discussion The correct profile file is crucial in code performance. Selection is based on several factors, including aerodynamic performance, structural stability, weight, durability, and ease of assembly and manufacturing. As the tip speed ratio increases, manufacturing complexity also increases. Other variables, such as wind speed and angular velocity, affect performance. Understanding these factors and their interrelationships is essential for achieving optimal design results. Fiberglass is identified as an ideal material for wind turbine blade manufacturing due to its durability, weight, availability, and cost-effectiveness. Accurate and precise mold modeling is crucial for manufacturing using local CNC machines. The findings support the research objectives of achieving affordability and accessibility in wind turbine blade design. The selected S822 airfoil demonstrates high aerodynamic performance and structural integrity, validated by both QBlade and ANSYS simulations. The torque results, as shown in Table III, indicate a strong correlation between the QBlade and ANSYS simulations, validating the reliability of the simulation models. These results confirm the aerodynamic efficiency and structural integrity of the S822 airfoil, which is critical for achieving cost-effective and high-performance wind turbine blades. The cost analysis further reinforces the economic feasibility of the proposed design, highlighting significant cost savings through the use of fiberglass and simplified manufacturing processes. The total cost of producing a 3.5 m wind turbine blade using the proposed methods is estimated to be 40% lower than traditional methods, making it more accessible for resource-limited regions. The performance of the blades was observed during preliminary testing on a 4-meter tower. The blades demonstrated good and stable performance, rotating at low wind speeds. However, due to financial constraints, specialized devices required for precise measurement of wind speed, direction, and rotational speed were not available. This limitation underscores the need for future acquisition of such equipment to validate performance metrics under real-world conditions. Conclusions Efforts focus on developing blade designs that balance performance and cost-effectiveness. Alternative materials and efficient manufacturing techniques are pivotal in achieving these goals. The study confirms that with proper design and analysis, wind turbine blades can be manufactured using accessible materials and simplified processes without compromising performance. The torque results from the simulation indicate reliable performance under various wind conditions, supporting the overall viability of the design. However, the data presented in this paper and the drawn conclusions are based on simulations, as there were no applicable devices to ensure that the wind turbine is stable after installation with various wind velocities. The research highlights the potential of using fiberglass and simplified manufacturing techniques to produce cost-effective and high-performance wind turbine blades, making renewable energy more accessible in resource-limited regions. Future Work Future research will explore several key areas to further enhance the performance and cost-effectiveness of wind turbine blades: Advanced Testing: Acquiring specialized testing equipment to validate performance metrics under real-world conditions. Blade Design and Materials: Further advancements in blade design, materials, and manufacturing techniques can be explored to improve performance and cost-effectiveness. 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