The new model is based on fundamental physics and can be used to optimize the design and operation of rotors in various applications.
Researchers from the Massachusetts Institute of Technology have developed a single impulse model that accurately reflects the aerodynamics of rotors even in complex situations, such as the influence of wind force, speed or changing the angles of the blades, writes interestingengineering.com.
This engineering the model is designed for rapid prototyping, control and optimization tools. The new model can help optimize the planning and operation of wind farms, which will lead to increased electricity production and lower costs.
One of the most exciting aspects of this new model is its potential for application. This means that wind farms will be able to optimize the settings of existing turbines in real time — without any hardware upgrade. In this way, it will be possible to maximize the output power while ensuring safety.
An earlier model, known as momentum theory, was developed in the 19th century and was widely used. However, it has limitations when it comes to higher forces and speeds. The new model addresses these limitations by combining careful computational aerodynamic modeling. For example, the original model assumed that the drop in air pressure just behind the rotor would quickly return to normal ambient pressure. However, as the thrust produced by the rotor increases, this assumption becomes increasingly inaccurate.
The researchers found that the original model became inaccurate at the Betz limit, which is the “theoretical maximum efficiency” for wind turbines. This limit indicates that no wind turbine can capture more than 59.3% of the wind's kinetic energy. According to Betz's prediction of where turbines should be operated, and within 10% of this operational setpoint that maximizes power, the theory breaks down and fails.
Interestingly, this new model changes the calculation of Betz's limit , implying that wind turbines may produce slightly more energy than previously thought. The new model explains strategies for maximizing power extraction from turbines that deviate from optimal alignment with the airflow — a scenario not accounted for by the Betz limit.
In addition, the MIT team developed a new way to overcome the limitations of the original model based on a simplified one-dimensional description of airflow. To do this, they used fundamental equations that were developed to predict the lift of three-dimensional wings.
The team has already started field tests using wind tunnels.