Mimicking whale tubercles in turbines

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Wave and tidal apparatuses have emerged in many forms in their quest to harness the renewable, fairly predictable energy of the ocean’s rhythms. The bumps, or tubercles, found on humpback whales flippers create vortices, helping the large cetaceans maintain lift as they cut through the sea [1].

Adding a series of ridges (tubercles) to the edges of a wind turbine blade could increase annual electrical production for wind farms by 20%, as tubercles allow turbines to overcome the three major limitations of wind power:

  • poor reliability when winds fall or fail
  • noise - especially tip chatter caused by tip stalling
  • poor performance in unsteady or turbulent air

Underwater turbines would eventually follow this example of marine biomimicry as well. Comparing bumpy vs. smooth blades in a 120-foot water tank at the U.S. naval academy, the researchers found the humpback-inspired blades won out. More research is needed, but the bumpy blades didn’t significantly hurt the performance of the turbine during stronger tides either. One thing the design has going for it, they say, is its simplicity. In the rough-and-tumble marine environments, mechanical complexity disfavors durability [1].

Whale fins fans

Figure 1: Industrial fan with humpback-inspired blades

Tubercle-like structures, designed by WhalePower, Toronto, Canada [2] on turbine blades would let them work at steeper angles without stalling or creating too much drag, according to the firm In low wind, blades with steeper angles could theoretically generate more power. Wind-tunnel tests show that, in some cases, adding tubercle-like bumps to model fins pushed back the stall angle by as much as 40% [3].

WhalePower's first Tubercle Technology product to come to the market is an industrial fan. WhalePower has licensed an Ontario company called Envira-North System's Ltd. to manufacture and distribute the first generation of fully optimized HVLS (high volume low speed) fans worldwide [4].



References

  1. 1.0 1.1 http://www.smartplanet.com/blog/intelligent-energy/tidal-turbine-mimics-whale-power/3974
  2. http://www.whalepower.com/
  3. http://www.windpowerengineering.com/design/mechanical/blades/rotor-blade-ridges-promise-more-turbine-power/
  4. http://www.whalepower.com/drupal/?q=node/2