MIT unveils new wind turbine model to enhance power in tough conditions

For more than a century, propellers and wind turbines have been designed using well-established aerodynamic principles. However, these principles have limitations, especially under extreme conditions.

Engineers at MIT have developed a new, comprehensive theory called the unified momentum model. It is based on theoretical analysis and validated using computational fluid dynamics modeling to ensure its accuracy and reliability.

It precisely depicts the aerodynamics of rotors, even under severe situations like high forces, speeds, or blade angles.

“It’s an engineering model developed for fast-running tools for rapid prototyping and control and optimization. The goal of our modeling is to position the field of wind energy research to move more aggressively in the development of the wind capacity and reliability necessary to respond to climate change,” said Michael Howland, who led the study.

The new model can help optimize the layout and operation of wind farms , leading to increased power production and reduced costs.

One of the most exciting aspects of this new model is its potential for immediate application. This means that wind farms will be able to optimize existing turbine settings in real-time — without any hardware update. This can help maximize power output while ensuring safety.

“This is what we’re so excited about, is that it has immediate and direct potential for impact across the value chain of wind power,” Howland added.

New model overcomes previous limitations

The previous model, known as momentum theory, was developed in the 19th century and has been widely used. However, it has limitations when it comes to higher forces and speeds.

The new model solves these constraints by combining thorough computational aerodynamic modeling.

The press release highlights some of the limitations of this older model. “For example, the original model had assumed that a drop in air pressure immediately behind the rotor would rapidly return to normal ambient pressure just a short way downstream,” it noted.

However, as the thrust force generated by the rotor increases, this assumption becomes “increasingly inaccurate.”

The researchers found that the original model became inaccurate at the Betz limit, which is a “theoretical maximum efficiency” for wind turbines. This limit indicates that no wind turbine can capture more than 59.3% of the kinetic energy in the wind.

“So, we have Betz’s prediction of where we should operate turbines, and within 10 percent of that operational set point that we think maximizes power, the theory completely deteriorates and doesn’t work,” Howland added.

Field tests underway

Furthermore, the MIT team devised a novel way to overcome the limitations of the original model, which was based on a simplified one-dimensional description of the airflow.

“To do so, they used fundamental equations that were developed to predict the lift of three-dimensional wings for aerospace applications,” the press release noted.

Interestingly, this new model modifies the calculation of the Betz limit, implying that wind turbines can produce somewhat more power than previously assumed.

“It’s interesting that now we have a new theory, and the Betz limit that’s been the rule of thumb for a hundred years is actually modified because of the new theory. And that’s immediately useful,” said Howland.

The new model elucidates strategies for maximizing power extraction from turbines that are deviating from the optimal alignment with the airflow — a scenario that the Betz limit fails to account for.

The team has already begun the field tests using wind tunnels.

The findings were published in the journal Nature Communications.