Frank FISH, et al.

Whale Flipper Rotor

Whalepower Corporation
27 Tyrrel Ave

Dr Frank E. Fish

1113 Winchester Trail, Downingtown, Pennsylvania 19383 (US). (Toronto Star) May 14, 2007


A Whale of a Tale


Tannis Toohey / Tyler Hamilton

Stephen Dewar, a Toronto executive with startup WhalePower Corp., holds a prototype of the company's blade, which mimics the aerodynamically efficient design of a humpback whale's fin.

Humpback flipper may be the key to better wind turbines.
A local company has designed a new type of wind-turbine blade that mimics the aerodynamic performance of a humpback whale's flipper, allowing a turbine to capture more of the wind's energy at much lower speeds.

The odd-looking blades, which have teeth-like bumps along their leading edge, are a dramatic departure from the smooth and sleek design that graces most wind turbines.

But Stephen Dewar, co-founder of Toronto-based WhalePower Corp., says the new approach could have a profound impact on wind-energy economics.

It means turbines manufactured with WhalePower blades would be capable of capturing energy where the wind is less strong, as conventional turbines tend to stall when wind speeds fall too low. Not only would this improve the business case for individual wind farms, it broadens the natural geography suitable for large-scale wind generation.

"This changes the game," says Dewar, adding that any system using a fan or turbine could also benefit from the new design. This includes everything from better turbines for hydroelectric generation to residential ceiling fans that use less electricity. "If we've got what we think we've got, then the range of applications is staggering."

The potential was enough for the Ontario Centres of Excellence and the Ontario Power Authority to contribute about $70,000 in early-stage research funding, and to encourage collaboration with the wind-engineering group at the University of Western Ontario. Independent third-party verification of the new blade's performance will be a crucial step toward commercial production.

"It's high risk, high return," says Ben Greenhouse, a manager of business development at OCE. "The business models will depend on how well this works."

Marine scientists have long marvelled at the acrobatics and agility of humpback whales, given these monster swimmers can reach 16 metres in length and weigh as much as 13 Hummer SUVs. Despite their enormous size, humpbacks are efficient hunters able to make sharp, tight turns.

It turns out the key to a humpback's agility lies in its long flippers, which feature a unique row of bumps or "tubercles" along their leading edge that give the wing-like appendages a serrated look. Researchers such as Frank Fish, a professor of biology at West Chester University in Pennsylvania, have found that the tubercles dramatically increase the whale's aerodynamic efficiency.

In one particular study conducted inside a controlled wind tunnel, Fish and research colleagues at Duke University and the U.S. Naval Academy saw 32 per cent lower drag and an 8 per cent improvement in lift from a flipper with tubercles compared to a smooth flipper found on other whales.

They also discovered that the angle of attack of the bump-lined flipper could be 40 per cent steeper than a smooth flipper before reaching "stall" that is, before seeing a dramatic loss in lift and increase in drag. In an airplane scenario, that's typically when you lose control and crash.

"That stall typically occurs on most wings at 11 or 12 degrees at the angle of attack," says Fish, adding that with the humpback design "stall occurred much later, at about 17 or 18 degrees of attack. So the stall is being delayed."

The implications are potentially enormous. Delayed stall on airplane wings can improve safety and make planes much more manoeuvrable and fuel-efficient. The same benefits can also be found on ship and submarine rudders, which explains the U.S. Navy's quiet involvement.

Dewar, a former broadcast journalist and co-producer of the 1980s nature series Lorne Greene's New Wilderness, is also a self-taught student of science with a fascination for linear and non-linear physics. He'd heard about Fish's research and, after a few chats over the phone, raised the idea of using the humpback design for wind turbines.

"I saw it as a natural application of this technology," recalls Fish.

One thing led to another and the duo formed WhalePower, with Fish taking on the role of president and Dewar handling business development and R&D from a headquarters in Toronto. Laurens Howle, Fish's research partner from Duke University, is an adviser and shareholder in the company who has contributed software for designing the new blades.

"We have an international patent going through everywhere," says Dewar. "It applies to all forms of turbines, compressors, pumps and fans."

WhalePower can retrofit blades on existing turbines or build new blades from scratch. Dewar says prototype tests to date have demonstrated "outstanding performance," most importantly during light winds, with the tubercle-lined blades capable of more than doubling performance at wind speeds of 8 metres per second.

"In fact, we're getting the kind of power (regular blades) produce at 8 metres per second at 5 metres per second," says Dewar, describing the results as "spooky" because of the dramatic improvement.

Fish says the better performance at low speeds is what makes the design stand out. "Since there are probably more days when you don't have gusty winds but instead have lower wind speeds, that means you can generate electricity on those lower energy days."

The reason is because the tubercles channel the wind as it hits the front or "leading" edge of the blade. The channels cause separate wind streams to accelerate across the surface of the blade in organized, rotating flows. These energy-packed vortexes seem to increase the lift force on the blade.

As well, the channels prevent airflow from moving along the span of the blade and past its tip, a troubling situation on smooth blades that can cause noise, instability and lead to a loss of energy. By keeping the airflow channelled, more of the wind is captured and noise is greatly reduced.

Dewar says the same aerodynamic principle applies to water flow through hydroelectric turbines – in other words, more electricity can be generated at lower water speeds, making it possible, particularly in a water-rich province like Ontario, to reconsider hydroelectric or pump-storage sites previously thought uneconomic for power generation.

"I'm honestly scared of making claims at this point," says Dewar. "The results are so good that we know everybody who knows anything about aerodynamics will think we're salting the goldmine." That's why third-party verification will be essential. The research, he says, has to be "bullet proof."

But even if WhalePower can prove beyond a doubt that its blade design is better, it doesn't necessarily ensure success. Wind-turbine manufacturers can't keep up with demand for current product, so there's little incentive to dramatically alter the design of their blades – at least not yet. There's also no incentive for banks to lend money to wind-farm projects taking a risk on a new blade design.

"It's like trying to break into the semiconductor business," says Kerry Adler, chief executive of Toronto-based wind developer SkyPower Corp.

"You're going to be hard-pressed to convince Dell Computer to put a new processing chip on their motherboards, particularly if it's not proven. In the wind industry, you'll have to have a thousand turbines in the ground before anybody gives (a technology) a second look."

WhalePower's hope of retrofitting existing turbine blades – an estimated $50 billion worth around the world – could also prove a tough sell. Adler says retrofitting a blade with tubercles would void the warranty. "Who's going to take that chance?"

Fish appreciates that WhalePower's approach may be considered radical, and he understands that many wind-turbine manufacturers will operate on the premise: If it isn't broken, don't fix it. But he says any business will change its course if the economic benefits are compelling enough.

"It takes a while to get any sort of new technology into the marketplace," says Fish, at the same time convinced that the study of biomimicry – the melding of biology and engineering – will help shape the future of energy production, transportation and medicine.

"We're starting to see more and more engineers grabbing on to this."

See also:
May 11, 2004

Mechanical engineer Laurens Howle with scale model of humpback whale flipper used in wind tunnel.

Mimicking Humpback Whale Flippers May Improve Airplane Wing Design

Laurens Howle

Humpback whale breaching the surface. Note bumpy tubercules on leading edge of flipper. Photo credit: William W. Rossiter, Cetacean Society International. (high bandwidth) (low bandwidth)

Humpback whale footage courtesy of Nan Hauser, Center for Cetacean Research and Conservation

DURHAM, N.C. -- Wind tunnel tests of scale-model humpback whale flippers have revealed that the scalloped, bumpy flipper is a more efficient wing design than is currently used by the aeronautics industry on airplanes. The tests show that bump-ridged flippers do not stall as quickly and produce more lift and less drag than comparably sized sleek flippers.

The tests were reported by biomechanicist Frank Fish of West Chester University, Pa., fluid dynamics engineer Laurens Howle of the Pratt School of Engineering at Duke University and David Miklosovic and Mark Murray at the U.S. Naval Academy. They reported their findings in the May 2004 issue of Physics of Fluids, published in advance online on March 15, 2004.

In their study, the team first created two approximately 22-inch-tall scale models of humpback pectoral flippers -- one with the characteristic bumps, called tubercles, and one without. The models were machined from thick, clear polycarbonate at Duke University. Testing was conducted in a low speed closed-circuit wind tunnel at the U.S. Naval Academy in Annapolis, Md.

The sleek flipper performance was similar to a typical airplane wing. But the tubercle flipper exhibited nearly 8 percent better lift properties, and withstood stall at a 40 percent steeper wind angle. The team was particularly surprised to discover that the flipper with tubercles produced as much as 32 percent lower drag than the sleek flipper.

The simultaneous achievement of increased lift and reduced drag results in an increase in aerodynamic efficiency, Howle explains.

This new understanding of humpback whale flipper aerodynamics has implications for airplane wing and underwater vehicle design. Increased lift (the upward force on an airplane wing) at higher wind angles affects how easily airplanes take off, and helps pilots slow down during landing.

Improved resistance to stall would add a new margin of safety to aircraft flight and also make planes more maneuverable. Drag -- the rearward force on an airplane wing -- affects how much fuel the airplane must consume during flight. Stall occurs when the air no longer flows smoothly over the top of the wing but separates from the top of the wing before reaching the trailing edge. When an airplane wing stalls, it dramatically loses lift while incurring an increase in drag.

As whales move through the water, the tubercles disrupt the line of pressure against the leading edge of the flippers. The row of tubercles sheer the flow of water and redirect it into the scalloped valley between each tubercle, causing swirling vortices that roll up and over the flipper to actually enhance lift properties.

The swirling vortices inject momentum into the flow, said Howle. This injection of momentum keeps the flow attached to the upper surface of the wing and delays stall to higher wind angles.

This discovery has potential applications not only to airplane wings but also on the tips of helicopter rotors, airplane propellers and ship rudders, said Howle.

The purpose of the tubercles on the leading edge of humpback whale flippers has been the source of speculation for some time, said Fish. The idea they improved flipper aerodynamics was so counter to our current doctrine of fluid dynamics, no one had ever analyzed them, he said.

Humpback whales maneuver in the water with surprising agility for 44-foot animals, particularly when they are hunting for food. By exhaling air underwater as they turn in a circle, the whales create a cylindrical wall of bubbles that herd small fish inside. Then they barrel up through the middle of the bubble net, mouth open wide, to scoop up their prey.

According to Fish, the scalloped hammerhead shark is the only other marine animal with a similar aerodynamic design. The expanded hammerhead shark head may act like a wing.

The trick now is to figure out how to incorporate the advantage of the tubercle flipper into manmade designs, said Fish.

The research team now plans to perform a systematic engineering investigation of the role of scalloped leading edges on lift increase, drag reduction and stall delay.


Turbine & Compressor Employing Tubercle Leading Edge Rotor Design

Classification:  - international: (IPC1-7): F03B3/12; F03D3/06; F03D11/00; H02K7/18; - European: F03B3/12; F03D1/06B; H02K7/18A2
Also published as: EP1805412 (A1) // EP1805412 (A0) //  CN101107441 (A) //  CA2587946 (A1)

Abstract ---  A turbine/compressor comprises at least one magneto-electric device and a drive train coupled to the magneto-electric device. At least one rotor blade is coupled to the drive train. The rotor blade has a shaped leading edge with a series of spaced tubercles formed therealong.

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