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nathaniel

whale power

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http://www.technologyreview.com/Energy/20379/

Quote


Marine scientists have long suspected that humpback whales' incredible agility comes from the bumps on the leading edges of their flippers. Now Harvard University researchers have come up with a mathematical model that helps explain this hydrodynamic edge. The work gives theoretical weight to a growing body of empirical evidence that similar bumps could lead to more-stable airplane designs, submarines with greater agility, and turbine blades that can capture more energy from the wind and water.

"We were surprised that we were able to replicate a lot of the findings coming out of wind tunnels and water tunnels using relatively simple theory," says Ernst van Nierop, a PhD candidate at the School of Engineering and Applied Sciences at Harvard. He coauthored the study with mathematics professor Michael Brenner and researcher Silas Alben.

The advantage of the humpback-whale flipper seems to be the angle of attack it's capable of--the angle between the flow of water and the face of the flipper. When the angle of attack of a whale flipper--or an airplane wing--becomes too steep, the result is something called stall. In aviation, stall means that there isn't enough air flowing over the top surface of the wing. This causes a combination of increased drag and lost lift, a potentially dangerous situation that can result in a sudden loss of altitude. Previous experiments have shown, however, that the angle of attack of a humpback-whale flipper can be up to 40 percent steeper than that of a smooth flipper before stall occurs.
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Prototypes of wind-turbine blades (see image below) have shown that the delayed stall doubles the performance of the turbines at wind speeds of about 17 miles per hour and allows the turbine to capture more energy out of lower-speed winds. For example, the turbines generate the same amount of power at 10 miles per hour that conventional turbines generate at 17 miles per hour. The tubercles effectively channel the air flow across the blades and create swirling vortices that enhance lift.

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WhalePower has also shown in demonstrations that tubercle-lined blades on industrial ceiling fans can operate 20 percent more efficiently than conventional blades can, and they do a better job at circulating air flow in a building. The results were dramatic enough to convince Canada's largest maker of ventilation fans to license the design, which will appear in a new line of products scheduled for release at the end of April.



How long till we see these on wingsuits?
My advice is to do what your parents did; get a job, sir. The bums will always lose. Do you hear me, Lebowski?

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This has been an ongoing field of research that has generated a lot of interest in other fields as well. Nike actually used some of what is described in the article in the making of a swimmers body suit for Olympic swimmers a few years back that made them more efficient in the water. If you search back about 4 years or so, someone else posted similar scientific findings in the forum that was along the same lines. It's interesting stuff and it just goes to show that mother nature sometimes does things for a reason. I still can't figure the reason for the platypus though;)

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