Guest Post: Whale Power by Daniel Arneman

Just how does a fifty foot long humpback whale dive deep and then leap from the water to the delight and amazement of whale watchers?  Certainly the whale is powerful, but there may be some other secrets to this 40 ton acrobat.

Scientist Dr. Frank E. Fish (yes – that’s his real name) went shopping for a gift one day, and spotted a humpback whale sculpture that seemed unusual.  On close examination, he discovered the sculptor had gotten the subject all wrong, carving bumps and ridges into the front of the whale’s fin.

Fish questioned the shopkeeper, explaining that accepted engineering standards require a smooth leading edge to cut through air or water.  The shopkeeper defended the sculptor, a meticulous whale watcher, and assured Dr. Fish that the humpback does indeed have bumps on the leading edge of its fins.

Perplexed, Fish investigated further and found that those bumps, or “tubercles,” have a dramatic impact on how the fin cuts through water.  It may not be a mistake after all!

Think back for a moment to a childhood car trip, waving your hand and arm out the window to feel the air rush by.  You noticed that if you held your hand out flat, then angled it up slightly, you could feel the lift of the air pushing against the bottom of your hand.  Make the angle too steep, and your hand would “stall,” being pushed backwards instead of up.

That “stall angle” is extremely important in the field of fluid dynamics, and it must be important to the humpback whale, because over time, its fins evolved a series of tubercles that actually increase the stall angle.  Put another way, the tubercles allow the whale to cut more sharply into the water, while still maintaining its forward momentum.  No wonder they can leap above the surface!

What does all of this whale talk have to do with renewable energy?  Well, a lot actually.

A company called Whale Power has created a wind turbine with “tubercle technology” built into the leading edge of the blades.  Just like humpback whale’s fins, the blades have a steeper stall angle and better aerodynamics, allowing them to harness more wind energy than their smooth competitors.  They produce more power, can operate at lower wind speeds, and are quieter than other turbines in their class.

Tubercle technology is SO good that the US Naval Academy is testing whale-inspired tidal generators that capture the energy in the ocean’s tide.

So next time you’re outdoors and see a plant or animal with an odd shape or unusual behavior, ask yourself how it got there.  Chances are very good that it’s no mistake – something’s life depended on it!

Daniel Arneman, PhD, is an environmental analyst at the University of North Carolina at Chapel Hill.  Daniel works to measure and manage the campus’s carbon footprint and he also has a passion for learning about biomimicry.

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