Plane crash blamed on 'turbulence' from wind farm
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The NLR aviation research group in the Netherlands published a report in 2020 which found that - for offshore helicopters - problematic turbulence was unlikely to be encountered beyond 6 turbine rotor diameters downwind of a single turbine. They proposed a safety factor of eight rotor diameters downwind of a multiple-turbine wind farm.
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In Germany , where I fly a lot, we have high concentration of Windmills ,in some cases very close to the landing circuit. Never heard or experienced any such "wake turbulence" nor ever heard of anyone complaining about it.
How to bring down a beautiful old PA22 like this is a shame , as with 150 HP you should be able to overcome any downdraft on a flat countryside. ..
How to bring down a beautiful old PA22 like this is a shame , as with 150 HP you should be able to overcome any downdraft on a flat countryside. ..
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In smaller planes, ultralights, you can feel the downstream turbulence. But it is not severe in a reaonable distance. Upstream, there is no effect on a plane. I tried it myself, flying in the height of the hub around a windmill.
Sprayed and flown around them a bit, never a problem with turbulence. Flown the Tri and Pacer a bit as well, the Piper Shortwings normally handle turbulence well.
There is a lot to learn on the subject of wind turbines and the effect on airflow downwind. It stands to reason that a wind turbine that generates 2-3 MW (1500 average households) must drag quite a large amount of energy from the movement of the mass and velocity of the air. Removal of energy in the relatively small area of the wind turbine rotor rotational area must have a profound fluid dynamics energy interchange with the free-flow airstream outside the rotor.
In turn the preservation or otherwise dissipation of these effects would depend on numerous factors such as size of rotor area, height of rotor, steadiness of wind velocity, gusts, vertical temperature gradient and stability of same, ground friction effects, geography and proximity of other wind turbines…to name just a few.
Yes, a lot to learn…much as we did learning about wake turbulence and persisting characteristics under some conditions that research and tests eventually revealed. We lost a few aircraft and folks prior to gaining a good understanding of the characteristics of the phenomenon was learnt the hard way.
The jury is still out…
In turn the preservation or otherwise dissipation of these effects would depend on numerous factors such as size of rotor area, height of rotor, steadiness of wind velocity, gusts, vertical temperature gradient and stability of same, ground friction effects, geography and proximity of other wind turbines…to name just a few.
Yes, a lot to learn…much as we did learning about wake turbulence and persisting characteristics under some conditions that research and tests eventually revealed. We lost a few aircraft and folks prior to gaining a good understanding of the characteristics of the phenomenon was learnt the hard way.
The jury is still out…
the condensation in the wake of the wind turbine is stated as being due to expansion cooling of the mass in the wake. I'm not sure I buy that argument but it has been made. The condensation is also possible just from the slight mixing that is necessary to get coalescence to occur, in perfectly still conditions condensation is delayed.
As energy is extracted from the airmass by a wind turbine, there will be a velocity deficit in the wake compared to the free stream flow that is not affected by the actuator disk of the turbine, and that will give a slight shear on transitioning from one condition to the other. The turbine does give a rotation to the mass flow in the wake which also results in loss of velocity in the free stream direction, and it gives some shear out of plane which would be dependent on entry height relative to the core, angle of entry, and flow/blade velocities.
As energy is extracted from the airmass by a wind turbine, there will be a velocity deficit in the wake compared to the free stream flow that is not affected by the actuator disk of the turbine, and that will give a slight shear on transitioning from one condition to the other. The turbine does give a rotation to the mass flow in the wake which also results in loss of velocity in the free stream direction, and it gives some shear out of plane which would be dependent on entry height relative to the core, angle of entry, and flow/blade velocities.
This Applied Physical Sciences Research Article indicates that wind speed loss behind a wind turbine working at operating conditions is in the order of 50% velocity. The included graphs give some visualization to the subject:
https://www.pnas.org/action/download...53113.sapp.pdf
https://www.pnas.org/action/download...53113.sapp.pdf
