Miniature Wind Turbine

• Relevant Skills: Solidworks, Rapid Prototyping, Iterative Design, Critical Thinking, Creativity

Situation

In the Fall 2023 semester, a team of seven students from the Department of Mechanical Engineering at the University of California, Berkeley, took on a challenging project to design, construct, and test a miniature wind turbine. This project was part of the course ENGIN 26: Three-Dimensional Modeling for Design, taught by Professor Kourosh Youssefi. The primary goal was to delve into the engineering principles underlying wind energy generation and develop a functional miniature turbine capable of producing the maximum amount of power within specified constraints.

Task

The project was structured into several critical tasks to ensure the successful completion of the wind turbine design:

• Blade Design:
  • Develop blades with a curved profile to maximize power generation, keeping the length within a maximum of three inches.
  • Optimize blade profile, angle of attack, and angle of twist for efficient performance.
• Tower Design:
  • Design a tower strong enough to support the turbine while maintaining a volume under 17 cubic inches.
  • Incorporate a modular structure to accommodate the limitations of 3D printing and ensure ease of assembly.
• Motor Housing Design:
  • Create a motor housing to fit the specified motor generator, including a precise 3/16-inch hole for bolt alignment with the motor's shaft.
• Simulation and Physical Testing:
  • Perform finite element analysis (FEA) to assess the stiffness and deflection of the tower.
  • Conduct physical tests to measure power output and structural integrity of the turbine.

Action

The project execution involved a series of well-defined steps, ensuring a comprehensive and meticulous approach to design and testing:

• Research and Conceptualization:
  • Conducted extensive research on wind turbine design principles and reviewed existing models to understand best practices and potential areas for improvement.
  • Organized brainstorming sessions to generate initial design concepts, focusing on maximizing power generation and ensuring structural stability.
• Design and Modeling:
  • Blades: Using SOLIDWORKS, the team designed three curved blades, each with a length of 2.5 inches. The design process involved optimizing the blades for an angle of attack of 15 degrees and an angle of twist of 21 degrees. These parameters were selected to balance lift and drag, ensuring maximum efficiency and stability.
  • Profile Selection: The blades featured a symmetric airfoil profile, chosen after considering the impact of airfoil shape on turbine performance. The symmetric profile was a safe choice to ensure balanced lift and drag characteristics under varying wind conditions.
  • Design Features: Utilized multiple reference planes and the loft feature in SOLIDWORKS to create the blades. The circular pattern feature ensured equidistant placement of the blades around the hub. Filleting the edges and embossing the group’s information on the hub added the final touches to the blade design.
  • Tower: The tower design drew inspiration from the Eiffel Tower's proven geometry, featuring a three-legged, radially symmetric structure to ensure stability and resistance to shearing forces. The modular design allowed for easy 3D printing and assembly.
  • Structural Design: The top-down cross-section was an equilateral triangle for radial symmetry, with a more open top structure to allocate material to support struts. Fillets were heavily utilized to improve aerodynamic profile and structural support. Basic male-female coupling systems were added for proper alignment during assembly.
  • Simulation: FEA in SOLIDWORKS tested the tower's stiffness and deflection. Analysis conditions included using acrylic material (due to SOLIDWORKS limitations), fixed geometry for tower feet, and a 9.81 N force applied at the motor housing's inner face. The tower showed minimal deflection, confirming its structural integrity.
  • Motor Housing: Designed to fit the motor generator precisely, the housing included a 3/16-inch hole for the motor shaft's alignment. The housing's design ensured it could securely hold the motor while accommodating the structural constraints of the tower.
• Simulation and Testing:
  • Finite Element Analysis (FEA): Conducted FEA to test the stiffness and deflection of the tower. The analysis confirmed that the tower was sufficiently stiff and would not deflect significantly under load, ensuring stability during operation.
  • Physical Testing: The turbine underwent rigorous physical testing to measure its power output and structural rigidity. The tests demonstrated that the turbine could generate a maximum power output of 0.3908 watts and withstand a 1 kg load with only a 0.94 mm deflection.
  • Power Output Testing: Secured the turbine on a test bench, measured wind speed using an anemometer, and collected RPM data with a tachometer. A power meter recorded voltage, current, and power, allowing for precise adjustments to find the peak power output.
  • Deflection Testing: Simulated wind load using weights attached via a pulley system. Incremental weights measured deflection, confirming the tower's ability to maintain stability under load.
• Collaboration and Documentation:
  • The team employed project management tools to coordinate tasks, track progress, and ensure timely completion of milestones.
  • Detailed documentation was maintained throughout the project, capturing design rationales, simulation results, and testing data comprehensively.
  • A comprehensive report and presentation were prepared to showcase the design, methodology, and findings of the project.

Result

The project successfully culminated in the creation of a fully functional miniature wind turbine, demonstrating the team's proficiency in mechanical design and SOLIDWORKS modeling. Key achievements included:

• Efficient Blade Design: The final blade design maximized lift and power generation through careful optimization of blade length, angle of attack, and angle of twist. The symmetric airfoil profile provided balanced performance under varying wind conditions.
• Robust Tower Structure: The tower design ensured stability and durability, meeting the stiffness and deflection requirements through thoughtful engineering and modular construction. The Eiffel Tower-inspired geometry provided excellent stability and resistance to shearing forces.
• Comprehensive Documentation: The team produced detailed documentation, including CAD drawings and technical specifications, which serve as valuable resources for educational purposes and future improvements. The documentation included detailed FEA results, physical testing data, and design rationales.

Conclusion

In conclusion, the miniature wind turbine project was a resounding success, meeting the specified performance goals and providing valuable insights into wind energy technology. The project demonstrated the team's ability to apply theoretical knowledge to practical challenges, using SOLIDWORKS for detailed design and analysis. The experience gained through this project contributes to the broader field of renewable energy by addressing the challenges of wind turbine design and performance optimization.

The project highlighted the need for continuous innovation in sustainable energy technologies and reinforced the importance of engineering education in addressing global energy challenges. As society moves towards cleaner and greener energy solutions, the insights gained from this project will be valuable contributions to ongoing efforts for a more sustainable future.