Sam Greenwood is a junior in mechanical engineering; when he’s not studying hard in the Duderstadt, he is one of a team of students consisting of Brandon Bartneck (Mechanical Engineering), Ian Fitzner (Mechanical Engineering), Jerry Chen (Aerospace Engineering), and David Carter (Aerospace Engineering) working under Professor Peter Washabaugh. This team is collaborating with Altaeros Energies—a Boston-based company working to develop high-altitude wind turbines. Because Michigan is a leader in Mechanical and Aerospace Engineering technologies, Altaeros chose to work with current Michigan students to help test their turbine designs.
Sam explained that most wind turbines follow a design that’s been around for decades; a blade connects to a tower that connects to the ground. Energy from the wind turbine travels down the tower towards the ground. While these models work, wind close to the ground is weaker and less consistent than it is at higher altitudes. With this information, Altaeros Energies decided that developing a high-altitude wind turbine would lead to capturing a more reliable and efficient source of energy from wind power. Their design looks something like a cross between a Macy’s Day Parade float and a food processor: a rotating blade hovers in the middle of an enormous, inflatable doughnut with Jetson’s-like fins. Tethers connect the doughnut to the ground, and energy is transferred down through them.
Because these turbines are very large, the logistics of making a full-scale prototype to test are complicated and expensive. Prof. Washabaugh, Sam, and the rest of the team decided to use rapid-prototyping technology to create small, to-scale models of the turbines for testing. In order to replicate inertial and buoyant characteristics of lighter-than-air systems on a small, lab-scale, the team opted to test in water, where inexpensive ballasted ABS plastic models could be designed to match these properties. Using a small tank of water to replicate the speed of high-altitude wind, students and Altaeros Energies were able to witness how their designs acted with varying “wind” speeds and altitudes. As they observed the results, the data was sent back to Altaeros Energies. From there Altaeros re-designed their models and sent them back to Sam and the team. Sam then re-submitted, and re-printed at the UM3D Lab. Sam explained that by using Rapid Prototyping technology, the team was able to consistently test parts, send feedback to Altaeros (where they would make changes as needed) and receive 3D-printed parts in a short amount of time. When the team wanted to experiment with the weight of the structure, they simply added holes to their design, re-printed the part, and added and subtracted lead rods to the form. Without the use of this technology, Sam and the student team would have spent most of their time constructing models out of wood or foam—taking valuable hours away from testing the designs.
These small-scale tests allow Altaeros Energies to revise their designs before doing full-scale tests like the one below:
(Video courtesy of Altaeros Energies)