Final Deliverable
Introduction
The main goal in project 1 was to create a Wind Turbine design for a large hydro company on Wolfe Island to power the city of Kingston, Ontario. The turbines had to be durable, efficient, and capable of generating large amounts of power. To create the best possible turbine for the hydro company, qualities such as low production cost, low inertia blades, and durable material were prioritised in the design of the turbines. There were also crucial constraints that ruled out potential designs for the wind turbines. The turbine farm had to be able to power the entire city of Kingston, and it had to be able to generate energy in an environment where wind frequently varied in speed and direction. The entire farm also needed to comfortably fit on Wolfe Island.
Conceptual Design – Justification of Selected Material
During the material selection process, four different MPI’s were calculated in order to choose materials with low mass, and low cost, while also having high strength, and stiffness. Using Granta software, we were able to find the top 5 materials for each MPI, and After taking each separate MPI into consideration, we came up the top 3 best materials for our turbine blades. Next, using an objective matrix, we found the overall best material to use for the turbine blade. High Carbon Steel was initially chosen as one of the top 3 materials because it consistently appeared as one of the top choices for the four MPI. Out of the three material finalists, High carbon steel scored the highest in a matrix that prioritised durability, low-density, and low-cost, in a decreasing order of importance. This result allowed us to conclude that high-carbon steel was the ideal material for the Turbine-Blades.
Finalized Problem Statement
Design a turbine blade for a wind turbine farm built by a large hydro company to power Kingston, Ontario. The blades should minimize inertia while also maximizing the number of rotor rotations. The blade size should not drastically affect the number of turbines in the farm. In addition, the material should be rigid to prevent major deflection of the blades. The turbine blades must be able to withstand environmental stress.
Justification of Technical Objectives and Material Performance Indices
The objective tree allowed us to start with our most basic requirements and slightly narrow down what we need to accomplish to achieve the most basic design goals. Restraints were added based on our assigned scenario to ensure the final product remained within the bounds of what was asked of us. Using Granta software, we were able to compare the viable materials based on their respective rankings with regards to yield strength, young's modulus, price and density. Low cost was necessary in order to make the production of wind turbines sustainable, while low density was necessary to ensure our blades have low inertia. High yield strength and high young’s modulus lend towards the durability of our turbine blades.
For our objective matrix we chose to rank our final materials by three weighted factors: durability, mass and cost (list in order of decreasing weight). We found durability to be more important than a low production cost turbine due to the additional costs of frequent reparations required for nondurable turbines. We added mass to the criteria to improve the efficiency of the turbine by limiting inertia, but this would make little difference if the turbine were unable to stay operational for long periods of time. As mass (low inertia) was directly requested in our assigned scenario, we weighed mass as a factor higher than cost.
Design Embodiment – Justification of Solid CAD Modelling
By running the deflection simulation and altering the thickness after each trial, we discovered that a 24.03717mm turbine blade thickness resulted in an exact deflection of 10mm. This allowed for the turbine blade to satisfy the deflection constraint. By choosing this thickness, we ensure that the blade can still deflect to maximize efficiency of the turbine but will not cause damage to the tower or blade. Deflection of the blade allows for increased surface area for the wind to hit, as well as increases the aerodynamic capabilities. By restricting the deflection to 10mm, we prevent increased stress and vibration of the blade while ensuring the blade will not hit the tower.
Concluding Remarks – Reality Check
After finishing project one, we found that there were many new skills that we learned. It was the first-time for our whole group using Autodesk Inventor and Granta. After completing the different milestones as well as attending our labs, we eventually became proficient in both Inventor and Granta. A lot of the times, the group would work on different tasks and at the end we would all come together to complete it. For instance, we all individually compiled the top five material choices from our individual charts and then by coming together, we were able to narrow our material choice down to the top three materials based on how often they appeared in our separate charts. We then used an objective matrix to narrow it down to one material thus finishing our task. Even though we were all relatively new to the tasks at hand, we did not let that overwhelm us and we basically took in everything one step at a time. We think that would be our takeaway message; do not let unfamiliar territories intimidate you, just take baby steps and keep moving forward. Additional engineering considerations that are worth exploring in the future are: fatigue from turbulent air and impact from foreign objects such as birds and hail. It would be interesting to figure out the additional steps we would have to take to account for foreign objects such as birds hitting the wind turbine.