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Thursday, July 10, 2008

Whales & Dolphins Inspire a Novel Design for Wind Turbines


Dolphins and whales have evolved over millions of years to maximize efficiency of movement through water. The human species has been trying to perfect streamlined designs for barely a century. Biologists and engineers, applying biomimicry, studied the flippers, fins and tails of whales and dolphins, and have discovered some features of their structure that contradict long-held engineering theories.

The shape of whale flippers with one bumpy edge has inspired the creation of a completely novel design for wind turbine blades. This design has been shown to be more efficient and also quieter, but defies traditional engineering theories.

Dr Frank Fish of West Chester University says that the shape of whale flippers has inspired the creation of a completely novel design for wind turbine blades.

"Engineers have previously tried to ensure steady flow patterns on rigid and simple lifting surfaces, such as wings. The lesson from biomimicry is that unsteady flow and complex shapes can increase lift, reduce drag and delay 'stall', a dramatic and abrupt loss of lift, beyond what existing engineered systems can accomplish," Fish said. "There are even possibilities that this technology could be applied to aeronautical designs such as helicopter blades in the future."

0707wind Large vortices are formed behind the troughs along the leading edge whereas flow behind the tubercles forms straight streamlines. The effect of these flow patterns induced by the tubercles is to delay stall. (Image credit: E.Paterson)

The research, which was funded by the US National Science Foundation and the US Office of Naval Research, looked specifically at the vortices formed in the wake of the marine mammals.

"In the case of the humpback whale, vortices formed from tubercles (bumps) on the front edge of flippers help to generate more lift without the occurrence of stall, as well as enhancing maneuverability and agility," he explained. "In the case of the tails of dolphins, vortices are formed at the end of the up and down strokes. These vortices are involved in the production of a jet in the wake of the dolphin that produces high thrust. By regulating the production of the vortices, the dolphin can maximize its efficiency while swimming."

Posted by Casey Kazan.

Original here

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