Whale of an Idea

Until it was replaced by petroleum in the late 1800s, whale oil was harvested in the millions of gallons for lamp fuel, to make candles and lubricate industrial machines. A century later, a Toronto-based company is again looking to the whale to not only generate energy but also conserve it. This time, however, the whale’s contribution is limited to the unusual geometry of the Humpback’s pectoral fins. In contrast to other whales and dolphins that have a smooth, streamlined leading edge to their fins, the Humpback developed large round bumps or tubercles that protrude from the front of its fin, giving it a serrated edge.

WhalePower developed and markets an airfoil design that incorporates these tubercles to fashion what the company claims is the next evolution in airfoil technology. According to Stephen Dewar, WhalePower co-founder and the company’s director of R&D, their design produces greater lift, creates less drag, stalls at a high angle of attack and is nearly silent. Still, he says, gaining acceptance of the radical concept has been a difficult process.

“At first, engineers and scientist in fluid dynamics ‘knew’ our design couldn’t work, even when presented with hard evidence,” Dewar says. “It’s taken a long time to penetrate people’s minds that this is not just a new design but new science.”

A million years of design iteration
It’s understandable that WhalePower’s design would be hard to accept. Since the beginning of wing design, airfoils were assumed to require a smooth leading edge. However, the Humpback fin is essentially a “wing” that helps the large mammal glide through the water and make the sharp turns needed to catch its pray. But for a 16-meter-long, 80,000-pound animal to be nimble, even in water, requires a hyper-efficient wing that won’t stall (i.e. drastically lose lift), even at extreme angles of attack.

WhalePower’s chief science officer and a mechanical engineering professor at Duke University, Laurens Howle, holds a prototype of the company’s distinctive, Humpback-inspired airfoil design.

It was this counter-intuitive wing design that caught the eye of biology professor Dr. Frank E. Fish, now WhalePower’s president. While shopping for a gift, he noticed a sculpture of a Humpback fin. As the director of the Liquid Life Lab at West Chester University of Pennsylvania, and an expert in biomechanics, he assumed the artist had mistakenly put the tubercles on the wrong side of the fin. After confirming that the sculpture was anatomically correct, he began questioning what possible use the bumps could have.

To answer that question, Dr. Fish teamed up with colleague Laurens Howle, a mechanical engineering professor at the Pratt School of Engineering at Duke University and an expert in fluid dynamics, as well as researchers at the U.S. Naval Academy. Using cross-sections of whale fins, the research team created idealized blade models for testing in a wind tunnel. Reported in the May 2004 issue of Physics of Fluids, the study found that the Humpback-inspired blade produced 32 percent less drag and an 8 percent improvement in lift compared to the smooth leading-edge flipper found on other whales and dolphins.