原创 Simulations show pilots should avoid wind farms

Wind turbines often kill birds, and efforts are being made to build new models that reduce bird mortality.

That raises the question whether wind farms might also generate enough turbulence to endanger light aircraft?

Examining the risks of wind farms may pose for ultra-light aircraft, researchers at the Fraunhofer Institute for Wind Energy and Energy System (Oldenburg, Germany) report that they have developed a simulation tool that can compute how power plants influence aircraft at various wind speeds and wind directions.

Researchers said the simulation can calculate how much turbulence wind farms generate, how they can alter wind speed and what influence these factors have on airplanes. After conducting simulations under various scenarios, Fraunhofer's Bernhard Stoevesandt said "we simulated various wind directions, two different wind speeds and five different flight trajectories in which the plane is under the rotor's sphere of influence for various lengths of time."

The German researchers created a computer model of the ground and a wind profile of the surrounding area where a wind farm is meant to be built. The model calculated how turbines alter wind conditions and create turbulence on a grid.

"The true skill is in the creation of the grid because the points on the grid where the computer makes the individual calculations must lie at exactly the right places," said Stoevesandt, specifying that the software must calculate the prevailing currents within several million grid cells that mutually influence each other. Other challenges include accurately depicting the trail – the turbulence and the change in wind speed behind the rotor – and assessing how this might affect a small aircraft flying near a wind farm.

A Fraunhofer simulation demonstrates the turbulence generated by wind turbines. The red area shows heavy turbulence, which is common near wind farms.
To validate the simulations, Stoevesandt said the trail from actual wind energy plants was measured at individual points behind the rotor, then the measurements compared with the simulations.

The researchers examined the effects of wind farms within an approximately 1,500m perimeter and an altitude of up to 500m.

The simulations also illustrate something any any good pilot should know: Steer clear of large obstacles on the ground.

- Anne-Françoise PELE