Whale-inspired bumps improve efficiency of ocean turbine blades

The bumpy protrusions, known as tubercles, on the leading edge of humpback whale flippers have already inspired more efficient wind turbine blades that are able to produce more power at lower speeds. Now, in a seemingly obvious move, researchers have found that that same principle can be applied to underwater turbine blades to more efficiently convert low velocity ocean tidal flow energy into electricity.

Even though tides are more predictable than wind energy and solar power, tidal power has not been as widely used due to its traditionally high cost and limited availability of sites with sufficiently high tidal ranges and velocities. The development of blades modified with tubercles by researchers at the U.S. Naval Academy (USNA) could help overcome both these problems and make tidal power generation more feasible by more efficiently converting low velocity tidal flows into useful electricity.

As with the wind power blades incorporating tubercle technology pioneered by WhalePower, the USNA researchers found that the addition of bumps to the leading edge of underwater turbines made them more effective at harnessing tidal power at low speeds. Importantly, the tubercle-fitted blades didn’t suffer a reduction in performance at high flow speeds or increase the mechanical complexity of the turbine.

"We designed a novel blade modification for potential turbine performance improvement, which was inspired by humpback whale flippers, with the addition of tubercles, or bumps, to the leading edge of each blade," explains Mark Murray, a Naval Academy engineering professor. “Previous research demonstrated the addition of biomimetically derived protuberances (technology that mimics nature) improved stall characteristics and aerodynamic performance," he said.

The USNA research team presented their findings at the American Physical Society's Division of Fluid Dynamics (DFD) meeting in Long Beach, California, last week.