There are several topics and comments on this forum that touch on dynamic soaring. Here is a topic for linking to those and to any other content on dynamic soaring.
Dynamic soaring for UAVs is a flight technique that enables continuous, powerless periodic flight patterns in the presence of a wind gradient. However, sufficiently large wind gradients are uncommon over land, while at offshore locations the largest wind gradients are located close to the ocean surface, thereby limiting the scope of practical application. An intrinsic feature of wind turbines is that they inherently produce very sharp wind gradients in the near wake. Therefore, in this paper, we propose and investigate periodic stationary dynamic soaring trajectories in the near wake of wind turbines. We additionally consider the potential of dynamic soaring for revitalizing the wind turbine wake. To this end, we apply periodic optimal control based on a simplified model for the glider dynamics and the wind profile in the wake. The cost function maximizes the revitalization of the wake. We compute optimal orbits for a range of different wing spans and different mass-scaling assumptions. The largest glider configuration, with a wingspan of 10 m and a mass of 222.6 kg, achieves a wake revitalization of about 0.94% of the total turbine thrust.
Introduction
Modern wind turbines are often clustered together in large farms in order to reduce balance-of-system costs and optimize the use of land or sea concession areas. However, wind turbines generate wakes that impair the efficiency of downstream turbines when spaced too closely together. In modern wind farms, with turbine spacings of 5 to 7 turbine diameters, overall efficiency losses due to wakes can be up to 40% and more, depending on wind direction and atmospheric conditions [2]. In the current work, we propose and investigate the potential of using glider planes to speed up wake recovery, by flying dynamic soaring loops between a wind turbine near wake and the surrounding free stream.[âŚ]
Anyone who has been involved in hang-gliding sees birds in a whole new way.
You can feel what the bird is thinking as it lands and flies, because itâs a case of âyup, been there, done thatâ.
Around here people stay up all day riding thermals. Wearing winter clothing, people launch at over 100 degrees F. , ride thermals up to 16,000 feet, and have to come back down when it gets too cold up there.
Anyway, what most people donât really notice becomes apparent - a gaggle of birds all circling in the same direction, none of them flapping their wings - we know they found a thermal and are riding in it without expending energy. Most people would just never notice the lack of flapping. Similarly, we see birds effortlessly riding the updraft when wind hits a ridge (ridge soaring), and we know what they are thinking as they play around and chase each other. When we see them lower their feet as they flare coming in for a landing, we see that they are just like us. Nothing new here folks. Soaring is an old concept. Staying well away from known dangerous obstacles like powerlines and wind turbines is rule number one!
We see this every day in the countryside, with the naked eye or binoculars.
Raptors are wrapping around in thermals and rising to spot possible prey.
To covering distance, some birds leave a thermal, glide to find another thermal, and so on, as gliders do.
On the other hand, the dynamic soaring of albatrosses is more difficult to observe if we are not in a boat in the sea. It takes place just above the sea, the bird covering distance by oscillating between two layers of air.