Good Thinking

Filter feeding basking shark inspires more efficient hydroelectric turbine

The Strait Power turbine inspired by the basking shark
The Strait Power turbine inspired by the basking shark
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A Straight Power hydroelectric turbine
A Straight Power hydroelectric turbine
Reale's Strait Power turbine model being tested at UM
Reale's Strait Power turbine model being tested at UM
The Strait Power turbine inspired by the basking shark
The Strait Power turbine inspired by the basking shark
Water enters the basking shark's mouth and is expelled through its gills
Water enters the basking shark's mouth and is expelled through its gills
Water flow of the Strait Power turbine
Water flow of the Strait Power turbine

Studying the bumpy protrusions on the fins of humpback whales has already led to more efficient wind and tidal power turbines and now nature is once again the source of inspiration for a new and more efficient hydroelectric turbine. The latest source of biomimicry is the basking shark, which industrial design student Anthony Reale has borrowed from to create "strait power," a water-powered turbine generator that tests have shown is 40 percent more efficient than current designs.

Despite being the second largest shark in the ocean, the basking shark is generally considered harmless to humans as it is a filter feeder. It swims with its mouth open to sift zooplankton, small fish and invertebrates from the water before the water is expelled through extended gill slits that nearly encircle its whole head. Although this flow of water assists in the shark’s swimming, Reale recognized that the shape of the shark’s body also played an important role.

With the basking shark’s jaw able to stretch up to 1.2 meter (3.9 ft) in width, a pressure differential is created as the shark swims. As with the wings of an airplane, the water pressure is greater along the straight bottom, while the curved surface of the shark’s body increases the distance the water has to travel, resulting in lower pressure across the shark’s top.

This pressure differential helps draw the water out of the basking shark’s gills and allows the basking shark to be only filter feeder shark that relies solely on the passive flow of water through its pharynx to feed. Other filter feeder sharks, the whale shark and megamouth shark, assist the process by suction or actively pumping water into their pharynxes.

With this in mind, Reale designed his ‘Strait Power’ turbine with a double converging nozzle or an opening within an opening. The water enters the turbine through the first opening and the second nozzle – like the shark’s gills – compresses the water and creates a low-pressure zone to draw the water through and generate more energy.

Reale came up with the design for his senior project at the College for Creative Studies (CCS) in Detroit and recently had the opportunity to put it to the test at the University of Michigan’s (UM) Marine Hydrodynamics Laboratory. The UM researchers with whom Reale collaborated were interested as they had been working on something similar to provide power for remote research camps in Alaska.

Subjected to 200 hours of testing in UM’s 100-yard-long (91 m), 22-foot-wide (6.7 m), 10-foot-deep (3 m) tow tank, Reale’s 900-pound (408 kg) turbine model made mostly of wood, screwed together and sealed with marine paint came out looking battered and bruised. But the results were promising with the researchers saying the design improved the power output of a single blade by around 40 percent – a figure that Reale expects to improve upon with future versions.

Reale has filed a patent for the technology and has designed five potential commercial uses of the Strait Power system ranging from a portable and collapsible version for charging small electrical devices designed for outdoor and military use, up to industrial versions with 10-foot (3 m) diameter blades for powering high-power electrical generators of 40,000 watts and higher.

Via designboom

Island Architect
Absolutely Bravo Anthony! This may well be one of the most important articles ever printed in Gizmag. The 40% advance is due to one thing similar to what Bill Allison did for wind power. Rather than try and build airfoils or hydofoils Mr. Real has taken the opposite approach, build angled resistors. That is the exactly the same principle that allowed Allison to achieve the theoretical maximum efficiency of 59% for his wind engines. Mr. Real may even find higher efficiencies with dead flat blades in section. If he researched what Allison did in wind power he might find fame in that field as well. Contrary to the logic expressed in the article water is non compressible but it can vary in velocity greatly. That is a key. I am proud that both Allison and Reale were Detroit Based and that the University of Michigan \"Engine\" School has been involved in both of their educations. It is time to recognize that the ubiquitous 3 bladed designs are perfect examples of very poor engineering design and it is disgusting that the politicians have latched on to that as the savior of humanity. It should be recognized that the spinnaker and the mainsail operate on two completely different principles. Anthony must receive proper and substantial backing at this stage of his life. Allison knew that stainless steel was essential and one wonders if the model had simply been used as armature for the creation of a negative mold for the fabrication of a fiberglass shell would have saved some grief. Bill Dickens
Kelly Williams
He\'s rediscovered the discharge accelerator or \"fall increaser\", developed before 1910, and recreated the Moody Ejector turbine. See More power is generated from the water that actually passes through the runner, but considerably more water is used altogether. Generally only applied in cases where there is occasionally excess water due to environmental fluctuations.
This looks like the aquatic version of a windmill previously mentioned on gizmag. The shape is different but they use the same concept of manipulating flow around the turbine to increase speed through the turbine.
Good research. One thing caught my attention in the written description that I\'ll point out in case it helps understand it better assuming something in the calculations didn\'t quite pan out. Classical airfoil theory attributes lift predominantly to the Bernoulli Effect where the air going over the top of a wing has a longer path and so must accelerate to meet up with the air it left at the leading edge. The faster moving air creates a low pressure zone and the pressure differential gives the lift. This has been shown to be incorrect. The air that goes under the wing has no \"appointment\" with the air going over the top to meet at the trailing edge and in fact it doesn\'t. The lift is caused by the angle of attack and a thing called the \"Coanda Effect\" where the air molecules at the wing interface tend to stick to the wing and the air molecules tend to stick to each other. The acceleration of the air as it is forced to curve creates a simple F=MA opposing force and that is the predominant force. The article can be found here. The new theory is supported by the fact that a wing will work perfectly well upside down as long as it has a suitable angle of attack. Not trying to be smart but maybe this will be useful to you. Cheers.
Oh, for crying out loud. Stop mentioning Allison. If his design was so much more efficient, why isn\'t it being used today in any wind turbine of any size, from small units generating a few hundred watts up through utility scale megawatt units? His 1970s-era patents have long since expired. Anybody can use the designs without paying royalties. The fact that nobody is doing so should tell you something, namely that his claims of increased efficiency were overstated.
Myron J. Poltroonian
The secret is in the blades. They\'re all wrong. Let me put it this way: \"Things that go \'Bump in the night\' \" work 24/7 (a phrase I hate) where it\'s night 24/7. N\'est ce pas?
Good luck with that patent - but I\'m pretty sure he\'s going to find out that since he\'s a student - his ideas belong to his instution - not himself... @warren52nz - mate - just because something doesn\'t make it in the marketplace, doesn\'t mean it\'s not better. Take yourself for example - you\'re using Microsoft Windows, a QWERTY keyboard, and fossil-fuel provided electricity right? Case in point.
\"40% more?\" - more than what? The blades in this thing only make up only about 20% of the surface area of the unit - so does \"40% more\" mean that it\'s really 62% *less* efficient than an equivalently sized conventional design? Sure - *if* you\'ve got unlimited fluid flow, it doesn\'t matter (unless you want to use the \"better-performing\" conventional design) - but since they didn\'t measure energy loss or compare it with anything else - the testing looks like a waste of time. The didn\'t even try the most obvious thing - run the blades minus the cowling. (or maybe they did, but didn\'t like the results?)
Yes, undoubtedly he is doing great work pointing out these design features, but doesn\'t that lateral-view \"cutaway\" diagram look remarkably similar to the bypass-fan jet engine that has been in service on aircraft for decades? Did all the experts on fluid-dynamics around the world never think of applying these principles to water-flow?
It\'s probably important here to define how we are measuring this improved efficiency; ie, more efficient than turbine blades of the particular diameter used? Or is it more efficient than a ducted area equivalent to the \'total intake area\". We may be talking about the turbine blade diameter, and possibly the case that a slightly larger turbine in a single duct that a size would also be 40% more efficient. Bottom line is, sounds great, I\'d love to see more clearly defined data!