Humpback whale secret may help helicopters fly faster
DLR Institute of Aerodynamics and Flow Technology / DLR Institute of Aeroelasticity
Helicopters can deliver military troops or rescue the wounded in tight spaces, but their rotating blade design also puts a hard limit on their speed and maneuverability. Now researchers have begun flight-testing an unlikely fix inspired by the underwater ballet of humpback whales.
The potentially cheap solution uses small bumps along the front edge of the helicopter blades similar to bumps found on the large pectoral fins of humpback whales. Such bumps give an aerodynamic edge that delays the moment of “stalling” when there’s not enough lift to keep the whale from sinking — or a helicopter from stalling out at top speeds.
“Stalling is one of the most serious problems in helicopter aerodynamics — and one of the most complex,” said Kai Richter from the DLR Institute of Aerodynamics and Flow Technology in Germany.
Helicopters face a speed limit because their backward-moving rotor blade goes against their forward motion of flight. That problem leads to turbulence and loss of lift, as well as strong forces acting on the rotor, which eventually cause the helicopter to stall out.
German researchers patented the bump idea for helicopters, under the name “Leading-Edge Vortex Generators.” Wind tunnel experiments led to a test flight with a helicopter carrying 186 rubber bumps —each less than a quarter of an inch long — glued to its four rotor blades.
“The pilots have already noticed a difference in the behavior of the rotor blades,” Richter said. “The next step is a flight using special measuring equipment to accurately record the effects.”
If testing goes well, existing helicopters could get a speed boost with simple retrofits. New helicopters could have the design built into their titanium blades during manufacturing.
The natural bump design already helps humpback whales swim at speeds of up to 16.5 miles per hour, or about five times faster than the fastest human swimmer.
“Research has shown that these bumps cause stalling to occur significantly later underwater and increase buoyancy,” said Holger Mai from the DLR Institute of Aeroelasticity in Germany. “Flow phenomena in water are similar to those in air; they just need to be scaled accordingly.”
Source: Innovation News Daily
Researchers Look to Convert Tidal Energy Into Electricity with Whale-Inspired Ocean Turbine Blades
Now lessons learned from the ocean’s largest mammals has inspired United States Naval Academy researchers to tackle one of the serious challenges of this technology: the low velocity associated with many tidal flows and the difficulty of extracting useful energy from low speed flows using current designs. They are presenting their findings at the American Physical Society’s Division of Fluid Dynamics (DFD) meeting in Long Beach, CA.
“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.”
The researchers’ modified blades proved to be more effective in extracting energy at low speeds. Importantly, the blades did not degrade performance at high flow speeds or increase the mechanical complexity of the turbine.
Applications of this research may include the development of turbine designs that are more effective in converting low velocity tidal flow energy into useful electricity and more economically feasible to deploy.
This project was conducted as an undergraduate independent research study by Ensign Timothy Gruber, who is currently attending Massachusetts Institute of Technology’s masters program, with Murray and Associate Professor David Fredriksson in the Naval Architecture and Ocean Engineering Department acting as his faculty advisors.
Found on ScienceDaily
Efficient Ocean Turbines inspired by Whale flippers
Biomimicry has given us everything from electronics displays to Velcro. Now we can thank nature for weaning us off unsustainable energy sources. Researchers from the United States Naval Academy have figured out that whale flippers can solve one of the most vexing problems associated with underwater tidal flow turbines.
Underwater turbines convert energy from the ocean’s tidal flow into electricity, but researchers in the past have had trouble grabbing useful energy from low-speed tidal flows. By adding humpback whale flipper-inspired tubercles (bumps) to the leading edge of each turbine blade, Naval Academy researchers found that they were able to extract more energy from low-speed waves—without hurting performance when waves rushed in at high speeds.
According to Science Daily, the research could lead to new underwater turbine designs. We’ll be watching WhalePower, a startup that designs tubercle-inspired wind turbines (pictured above). The company’s whale-based designs can already be seen in the Tubercle Technology HVLS (High Volume Low Speed) fan, a product sold in partnership with industrial and agricultural fan manufacturer EnviraNorth Systems Ltd. And that’s just the beginning. WhalePower claims that more whale-inspired fans, turbines, and rotors will all be available soon.
Found on FastCompany