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
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
http://www.frenchriverland.com/fall_increaser_moody_ejector_turbine.htm
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.
http://www.gizmag.com/flodesign-high-efficiency-wind-turbine-based-on-jet-engine-technology/10556/
The shape is different but they use the same concept of manipulating flow around the turbine to increase speed through the turbine.
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.
http://amasci.com/wing/airfoil.html
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.
@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.
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?)
Bottom line is, sounds great, I\'d love to see more clearly defined data!