Whales inspire better blade designs
The bumps on a humpback's fins inspire a new line of green-tech blades for turbines, fans, and maybe the home.
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But when the shop manager produced a photograph that showed the leading edge of the long fins was indeed serrated like the teeth on a saw, Dr. Fish was intrigued and decided to investigate.
He discovered that these bumps, called tubercles, are this creature's secret weapon, allowing a whale the size of a school bus to make tight turns and capture prey with astonishing agility.
Fish, a biology professor at West Chester University of Pennsylvania, is now using this technology perfected by nature to produce fans with serrated blades that use 20 percent less electricity than traditional models. This finding contradicts conventional designs that strive for the smoothest possible edges.
To understand this phenomenon, imagine airplane wings. Pilots increase the angle of the airfoil to provide more lift. But when the angle gets too steep, the air current drags on the wing, suddenly reducing the lift and causing the aircraft to stall.
Fish found that humpback fins act a little differently. He and his colleagues tested a scale model of the whale flipper in a wind tunnel. To their surprise, the experiments revealed that significant drag occurs at a much steeper angle on the humpback fin than it does on a sleek flipper. Each tubercle redirects and channels air over the flipper, creating a sort of whirling vortex that actually improves lift, Fish says.
Calling it "simple aerohydrodynamics," he explains that "we can get a higher angle with a higher lift force," giving the humpbacks more power and maneuverability than smooth-finned whales.
"These bumps were thought of as anatomical anomalies, but they do modify the flow and they do it in ways that are beneficial to the whale," says Fish.
The technology can be used in a huge range of machines such as turbines, compressors, pumps, and fans that use blades or rotors – most anything that cuts through air, water, steam or oil, says Fish.
"This can be applied to any lifting surface, like airplane wings or windmill blades or sailboat masts," he says.
The US Naval Academy participated with Fish in one study and is interested in possible applications for ship and submarine rudders.
Fish teamed up with a Canadian businessman to form WhalePower, a Toronto-based company that markets the technology. Envira-North Systems, Canada's largest supplier of industrial ceiling fans, with 75 percent of the market, recently licensed the design for a new line of fans that measure up to 24 feet in diameter.
"There was a 20 percent drop in energy use, a significant drop in noise decibels, and overall distribution of air was more even," says Envira-North CEO Monica Bowden. The increased efficiency also means the new fans will have five blades instead of 10, making them cheaper to manufacture.
Envira-North expects to start shipping in October and phase out production of conventional fans. The company is fielding calls from potential customers in Britain, China, Saudi Arabia, and Brazil – all new markets for Envira-North.
"Everybody is interested in green technology right now," says Ms. Bowden.
WhalePower cofounder Stephen Dewar says that while the 1-½-year-old company hasn't issued a single press release, they've already been contacted by companies around the world – from computer manufacturers interested in putting tiny fans inside laptops to companies with immense server farms looking for cheaper cooling options.
"We expect quite a wide range of fans to hit the market within a year," says Mr. Dewar. We may even see humpback-inspired fans in our own homes one day.
The company is also developing wind turbines that produce more energy and are quieter than standard turbines.
Last year, WhalePower mounted a wind turbine with its patented serrated blades stretching 33 feet across at the Wind Energy Institute of Canada's testing site on Prince Edward Island on the Atlantic coast.
Final results won't be released until year end, but Fish says, "We can actually get more power out of the wind.