A mini wind farm is about to sprout in White Field on the north edge of the ND campus this spring — if it hasn’t already. A couple of 30-foot rotor blades spinning on two 54-foot-high stands will generate about 50 kilowatts of power once the wind turbines go online.
“We are not going to light up the campus,” says Professor Thomas Corke, director of Notre Dame’s Institute for Flow Physics and Control (FlowPAC), “but what we make, the University can have.” The wind-generated electricity will be enough for about six houses, or 1/40th the power demand of the wind tunnels that are housed in FlowPAC’s White Field lab.
The turbines are being built to test rotor designs that incorporate devices known as “plasma flow actuators.” These high-tech gizmos, which look like a swatch of duct tape on the rotor blade, ionize the surrounding air. This alters the blade’s aerodynamics, which, in turn, should increase the turbine’s efficiency.
In fact, Corke and his ND colleague, Professor Robert Nelson ’64, ’66M.S. have run computer simulations that show a potential 20 percent increase in efficiency from the plasma flow actuators.
“It turns out that the single feature that determines the cost of a wind turbine is the weight of the rotor,” Corke notes. “So the larger you make them, the more power they generate, but the heavier and consequently more expensive they become.”
Plasma flow control, however, offers a handy solution to the problem. Acting like virtual flaps on a wing, the actuators modify air flow across the turbine blade. The increased efficiency allows for a smaller, lighter and, therefore, less expensive turbine. “Simply by reducing the diameter, we reduce the weight and the cost,” Corke says.
The actuators also have the potential to extend the life of the turbine. By reducing the effects of wind gusts, they lessen the aerodynamic forces that, left unchecked, can cause metal fatigue and cracks in the rotor blade.
The beauty of Corke and Nelson’s plasma actuators is that the “duct tape swatches” could easily be retrofitted onto existing wind turbines. In fact, Sorian, a start-up company headquartered at Innovation Park adjacent to campus, has partnered with Notre Dame to further develop and market the technology.
In addition to retrofit devices, Corke, Nelson and their colleagues are developing novel rotor designs that incorporate plasma flow control. For example, instead of the familiar blades, the new rotors might use cylinders.
“It takes some effort to convince people to try shapes that are aerodynamically bad, in and of themselves, but better once we add plasma flow control. This kind of outside-the-aerodynamic-box thinking is something we’ve been pushing for years,” Corke says.
Wind power accounts for about 1.5 percent of the electricity produced in the United States. By way of comparison, 33 percent of the power consumed in Germany, Spain and Denmark comes from wind.
Corke and Nelson estimate that if the United States produced 20 percent of its power from wind, as the Department of Energy proposes, and if the new turbines incorporated plasma flow control, the number of new wind turbines needed could be reduced by 50,000, saving the nation up to $15 billion.
John Monczunski is an associate editor of Notre Dame Magazine. Email him at jmonczun@nd.edu.