Wind farms: A danger to ultra-light aircraft?

Aug 03, 2012
The simulation reveals the turbulence generated by wind turbines. The red beam indicates heavy turbulence - which is particularly common behind the wind power plant. © Fraunhofer IWES

Airfields for ultra-light aircraft are typically constructed on level ground – and so are wind farms. However, do wind power plantsgenerate turbulence that could endanger lightweight planes? A simulation can compute how these power plants influence aircraft at various wind speeds and wind directions.

For a motorized hangglider or a one-seater weighing 300 kilograms: the business of flying by ultra-light aircraft is booming. That is also why numerous airfields are applying for the license to host these lightweight gliders. Most of these airfields are located on flat land, which is also the preferred terrain for wind power plant. However, these facilities could turn out to be a risk factor for aviators, especially when it comes to takeoff and landing: On the one hand, the “pilfer” the winds from the planes, because aft of such facilities are considerably lower. If the aircraft fly in the region behind the rotor, then they will suddenly find themselves contending with an entirely new aerodynamic situation. On the other hand, rotors produce turbulence in the air that could equally interfere with the aircraft.

Simulation calculates turbulence

The extent to which wind turbines impact ultra-light aircraft is an especially pertinent question now at the Linnich-Boslar ULV Airfield, where a major wind farm is slated for construction in close proximity. The operator, BMR Windenergie, wants to be sure – prior to construction – that no risk imperils the aviators. On behalf of this company, researchers at the Fraunhofer Institute for Wind Energy and Energy System Technology IWES in Oldenburg developed a simulation that enables them to calculate what turbulence these facilities generate, how they alter wind speed and what influence these factors have on airplanes. “We conducted these simulations under a variety of scenarios,” says Dr. Bernhard Stoevesandt, head of department at IWES. “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.”

Complex grid model

For the simulations, the researchers initially created a computer model of the ground and a wind profile of the surrounding area where the wind farm is to be built. A grid was placed over the model. The computer calculates how the power plants alter wind conditions and turbulence at various points on the 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,” explains Stoevesandt. The complexity of the simulation is enormous – the software must calculate the prevailing currents within several million grid cells that mutually influence each other. Other challenges consist in properly depicting the trail – that is, the turbulence and the change in wind speed behind the rotor – and determining how it affects the airplane. “To validate the simulations, the trail from actual wind energy plants was measured at various individual points behind the rotor, and the measurements compared with the simulations,” affirms Stoevesandt. “Each of the data matched well.”

Altogether, the scientists examined the effects of within an approximately 1500 meter perimeter and an altitude of up to 500 meters. By comparison, the hub of the rotor is 123 meters in height. The finding: At the Linnich-Boslar landing field, the turbulence generated by the turbines is lower than the ordinary turbulence of the surrounding environment. Still, this finding can only be applied to other airports to a limited extent, because the surrounding terrain has a tremendous impact on the trail; unlike flat terrain, the trail is different where the landscape is forested or hilly. “The simulations would have to be commensurately adjusted for those kinds of airfields,” says Stoevesandt.

Explore further: Researchers use 3D printers to create custom medical implants

add to favorites email to friend print save as pdf

Related Stories

Computer model optimizes wind farm

Jul 25, 2011

A new software from Siemens will improve wind farms’ energy yields and extend their service life. When the wind causes the huge rotors to turn, it generates turbulence, which interferes with the operation ...

Optimizing large wind farms

Nov 23, 2010

Wind farms around the world are large and getting larger. Arranging thousands of wind turbines across many miles of land requires new tools that can balance cost and efficiency to provide the most energy for ...

Wind farms lift the temperature in their region

Apr 30, 2012

Wind turbines can modify the local climate by warming the atmosphere, according to a study that revealed an increase in temperature of 0.72 degrees over a region of Texas where four large wind farms have been ...

Tilting at wind farms

Jan 07, 2009

A way to make wind power smoother and more efficient that exploits the inertia of a wind turbine rotor could help solve the problem of wind speed variation, according to research published in the International Journal of ...

Power generation is blowing in the wind

Jan 17, 2012

(PhysOrg.com) -- By looking at the stability of the atmosphere, wind farm operators could gain greater insight into the amount of power generated at any given time.

Recommended for you

For secure software: X-rays instead of passport control

22 hours ago

Trust is good, control is better. This also applies to the security of computer programs. Instead of trusting "identification documents" in the form of certificates, JOANA, the new software analysis tool, examines the source ...

Razor-sharp TV pictures

Aug 21, 2014

The future of movie, sports and concert broadcasting lies in 4K definition, which will bring cinema quality TV viewing into people's homes. 4K Ultra HD has four times as many pixels as today's Full HD. And ...

Michigan team finds security flaws in traffic lights

Aug 21, 2014

What if attackers could manipulate traffic lights so that accidents would happen with mayhem as the result? That is a question many would rather put off for another day but authorities feeling responsible ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

ormondotvos
not rated yet Aug 03, 2012
UltraLights need to be stable enough for normal wind conditions, such as downwind of tall trees, cliffs, tall buildings, and downdrafts, dust devils and large airplane turbulence.

If they aren't airworthy, they're grounded. The operator skills must be checked for competence under such conditions.
rwinners
1 / 5 (1) Aug 03, 2012
Oh come on. Do ultras fly IFR? Do they fly at night? Are ultralite pilots blind?

Well, perhaps there are some stupid ones, at that. Ever heard of natural selection?