Whale-Fin Turbines

A humpback whale's flipper looks flawed. Its leading edge is lined with bumps called tubercles, and textbook aerodynamics says bumps should add drag. They do the opposite. The tubercles split the oncoming flow into tidy channels, which keeps the flipper gripping the water at steep angles where a smooth edge would stall. A 30-ton animal turns on a dime. Engineers borrowed the trick: turbine and fan blades with bumpy edges, built by WhalePower, squeeze up to 20% more output from the same wind and run quieter.