'Waggling' Wings Could Save 20% in Fuel Consumption

Image credit: Jstockard
Aircraft 'Waggle Effect' Can Reduce Fuel Consumption 20%
Everybody knows that flying is an energy intensive activity. Unfortunately, many long awaited innovations in fuel-efficient aviation are of the more far-fetched variety - I'm thinking airships, blended wings etc. Yet it's long been noted that the addition of 'winglets' to aircraft wings can reduce fuel consumption - in fact, Southwest Airline's use of winglets even earned them a nomination from one of our readers for our Unexpected Green competition. But that's not the only simple improvement that could cut fuel use - now a team from the University of Warwick in the UK claims that 'waggling' air accross aircraft wings could cut skin friction drag by 40%, offering a 20% savings in fuel consumption and emissions. Read on for more details.
Green Car Congress brings us more details on this cutting-edge aviation research from the UK that could lead to significant airplane fuel efficiency improvements in the medium to short term:

Aircraft wings which redirect air to waggle sideways over their surfaces could significantly reduce drag and thus cut fuel consumption and emissions by 20%, according to researchers at the University of Warwick (UK). The new approach, which promises to dramatically reduce mid-flight drag, exploits Helmholtz resonance—the same phenomenon that happens when blowing over a bottle—to produce micro-scale jet flows in response to turbulent noise.

The main contributor to aerodynamic drag, and thus fuel consumption and emissions, is fine-scale turbulence that exists very near to the aircraft’s surface during cruise. The Turbulence Flow Control group at the University of Warwick has been studying non-powered (passive) flow control actuators as a means of reducing drag for some time, with the goal of developing flow-control technologies capable of major drag reductions on passenger jet aircraft.

Warwick is focusing on passive actuators because if an actuator is to be used on an aircraft, it must save more energy (in reduced drag) than it requires for its operation. Unfortunately, the researchers at Warwick note, many powered devices that have been developed for the drag-reduction application are unlikely to satisfy this fundamental net-saving requirement.

In a project funded jointly by the Engineering and Physical Sciences Research Council (EPSRC) and Airbus, Warwick and other universities are investigating the potential of using new types of passive devices for turbulent drag reduction. One of the ideas under investigation was the use of Helmholtz resonance.

Dr Duncan Lockerby, one of the researchers, said in a press release about the waggle wing research that they weren't entirely sure why the waggle effect was so pronounced, but "with the pressure of climate change we can’t afford to wait around to find out. So we are pushing ahead with prototypes and have a separate three year project to look more carefully at the physics behind it. Here's hoping they can figure out a way to make it work in the real world!

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