Whale-inspired bumps improve efficiency of ocean turbine blades
The bumpy protrusions, known as tubercles, on the leading edge of humpback whale flippers have already inspired more efficient wind turbine blades that are able to produce more power at lower speeds. Now, in a seemingly obvious move, researchers have found that that same principle can be applied to underwater turbine blades to more efficiently convert low velocity ocean tidal flow energy into electricity.
Even though tides are more predictable than wind energy and solar power, tidal power has not been as widely used due to its traditionally high cost and limited availability of sites with sufficiently high tidal ranges and velocities. The development of blades modified with tubercles by researchers at the U.S. Naval Academy (USNA) could help overcome both these problems and make tidal power generation more feasible by more efficiently converting low velocity tidal flows into useful electricity.
As with the wind power blades incorporating tubercle technology pioneered by WhalePower, the USNA researchers found that the addition of bumps to the leading edge of underwater turbines made them more effective at harnessing tidal power at low speeds. Importantly, the tubercle-fitted blades didn’t suffer a reduction in performance at high flow speeds or increase the mechanical complexity of the turbine.
"We designed a novel blade modification for potential turbine performance improvement, which was inspired by humpback whale flippers, with the addition of tubercles, or bumps, to the leading edge of each blade," explains Mark Murray, a Naval Academy engineering professor. “Previous research demonstrated the addition of biomimetically derived protuberances (technology that mimics nature) improved stall characteristics and aerodynamic performance," he said.
The USNA research team presented their findings at the American Physical Society's Division of Fluid Dynamics (DFD) meeting in Long Beach, California, last week.
About the Author
Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.
All articles by Darren Quick
Some more Biomimicry to the rescue, why not let natural selection figure it out.
3D profile RC foam planes have had zig zag leading edges for several years.
\"biomimetically derived protuberances\" In other words they put falsies on the blades. ;)
Man should be sufficintly humble to acknowledge that animals in nature have developed very efficient methods of motion, such as with the flippers of the humpback whale. Any improvement on the efficiency of blades to function better at lower air/water flow rates should be appreciated. The cost factor to manufacture such blades now has to be considered.
I think that the noise level of this type of blade needs to be examined carefully, especially in light of the present adverse effects to the health of people living close to conventional wind farms.
On TV i saw that where cold currents rise from the deep the current can be at 2 meters per second! constantly! that is HUGE energy..., say off of africa and when the continental shelf drops off from 50 meters to 1 kilometer in a cliff.
2 meters per second is about 3000 or 4000 watts per square meter day and night, for a turbine with a 10 m^2 propeller surface area it would be 40 000 watts. pretty good. only problem is that under water, algea and crud grows fast on everything.
A company in the HVLS fan business uses these tubercles on the leading edge of their blades. They claim it increases the effectiveness of the fan. However, they use an aluminum extrusion for the blade, which is nowhere near optimal. But it is nice to see some science to back up ways to tweak perfromance.
Bruce H. Anderson
if currents are moving at 2m/s then that would be about 20 HP or about 15000 watts
1m^3 weighs about 2000 lbs, 2m/s = about 6 ft Sect
in one sec 12000 ftlbs of work have been done
1 hp = 550 ft lbs /sec 12000/550 = 21.8 hp
A 750 watts per HP it is over 15 KW per m^2
I don\'t know what eff factors you are using to calculate your O/P.
I just spent the last 3 years restoring a sailboat and I declare, (and it says so in my thread,\" a folkboat found me\", on the,\" WoodenBoatForum\" website), that my folkboat is the first one in the world to have tubercles all down the front edge, or the forefoot as it is called, below the stem and above the ballast on the leading edge, and I did get this idea several years ago whilst surfing in Hawaii. Just off the reef I was surfing was a Humpback whale hangin around and making him/her self quite visible. It was close enough to see those familiar irregularities on its body, predominantly its pectoral fins, that are tubercles.
I researched these things a bit and decided that many billions of years in the making has gotta be worth emulating as nobody knows fluid hydrodynamics and how to get about beneath the surface of the waves, like the mighty Humpback, with its massive form creating those tight turns with which to blow a stream of bubbles in an air curtain that surrounds and concentrates its prey before rising and engulfing them.
So I have big knobbly wood and epoxy lumps irregularly, as close to the whales as I could make, placed down the front edge of \"FURTHER\", my boats name, and I am certain it aids noticeably in the performance of her hull.
It is nice to take something from the sea without killing or destroying it. Go the Humpback. Sail on Further.
Kerry Emmerson. Amateur Wooden Boat Builder, and many other things.
New Zealander livin in CA
hey do you have a 3d model of the blades on solid works or the dimesions of some sort
i would like to build your blades for home project
Jean-Pierre De La Chaumette
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