Flexible wings driven by simple oscillation may be viable for efficient micro air vehicles

November 22, 2010
Georgia Tech mechanical engineering assistant professor Alexander Alexeev (right) and graduate student Hassan Masoud used three-dimensional computer simulations to examine the lift and hovering aerodynamics of flexible wings driven at resonance by sinusoidal oscillations. Credit: Georgia Tech/Gary Meek

In the future, tiny air vehicles may be able to fly through cracks in concrete to search for earthquake victims, explore a contaminated building or conduct surveillance missions for the military. But today, designing the best flying mechanism for these miniature aerial machines is still a challenging task.

Creating micro-scale air vehicles that mimic the flapping of winged insects or birds has become popular, but they typically require a complex combination of pitching and plunging motions to oscillate the flapping . To avoid some of the design challenges involved in mimicking insect wing strokes, researchers at the Georgia Institute of Technology propose using flexible wings that are driven by a simple sinusoidal flapping motion.

"We found that the simple up and down wavelike stroke of wings at the is easier to implement and generates lift comparable to winged insects that employ a significantly more complex stroke," said Alexander Alexeev, an assistant professor in Georgia Tech's School of Mechanical Engineering.

Details of the flapping motion proposed by Alexeev and mechanical engineering graduate student Hassan Masoud were presented on Nov. 22 at the 63rd Annual Meeting of the American Physical Society Division of Fluid Dynamics. A paper published in the May issue of the journal Physical Review E also reported on this work, which is supported in part by the National Science Foundation through TeraGrid computational resources.

In nature, flapping-wing flight has unparalleled , agility and hovering capability. Unlike fixed-wing and rotary-wing air vehicles, micro air vehicles integrate lifting, thrusting and hanging into a flapping wing system, and have the ability to cruise a long distance with a small energy supply. However, significant technical challenges exist in designing flapping wings, many motivated by an incomplete understanding of the physics associated with aerodynamics of flapping flight at small size scales.

"When you want to create smaller and smaller vehicles, the aerodynamics change a lot and modeling becomes important," said Alexeev. "We tried to gain insight into the flapping aerodynamics by using computational models and identifying the aerodynamic forces necessary to drive these very small flying machines."

Alexeev and Masoud used three-dimensional computer simulations to examine for the first time the lift and hovering aerodynamics of flexible wings driven at resonance by sinusoidal oscillations. The wings were tilted from the horizontal and oscillated vertically by a force applied at the wing root. To capture the dynamic interactions between the wings and their environment, the researchers used a hybrid computational approach that integrated the lattice Boltzmann model for and the lattice spring model for the mechanics of elastic wings.

The simulations revealed that at resonance -- the frequencies when a system oscillates at larger amplitudes -- tilted elastic wings driven by a simple harmonic stroke generated lift comparable to that of small insects that employ a significantly more complex stroke. In addition, the simulations identified one flapping regime that enabled maximum lift and another that revealed maximum efficiency. The efficiency was maximized at a flapping frequency 30 percent higher than the frequency for maximized lift.

"This information could be useful for regulating the flight of flapping-wing since high lift is typically needed only during takeoff, while the enhanced aerodynamic efficiency is essential for a long-distance cruise flight," noted Masoud.

To facilitate the design of practical micro-scale air vehicles that employ resonance flapping, the researchers plan to examine how flapping wings can be effectively controlled in different flow conditions including unsteady gusty environments. They are also investigating whether wings with non-uniform structural and mechanical properties and wings driven by an asymmetric stroke may further improve the resonance performance of flapping wings.

Explore further: Scientist uses dragonflies to better understand flight

Related Stories

Scientist uses dragonflies to better understand flight

February 20, 2006

If mastering flight is your goal, you can't do better than to emulate a dragonfly. With four wings instead of the standard two and an unusual pitching stroke that allows the bug to hover and even shift into reverse, the slender, ...

Micro flying robots can fly more effectively than flies

August 1, 2009

There is a long held belief among engineers and biologists that micro flying robots that fly like airplanes and helicopters consume much more energy than micro robots that fly like flies. A new study now shows that a fly ...

Artificial butterfly in flight and filmed (w/ Video)

May 20, 2010

A group of Japanese researchers, who publish their findings today in Bioinspiration & Biomimetics, have succeeded in building a fully functional replica model - an ornithopter - of a swallowtail butterfly, and they have filmed ...

Recommended for you

Smart home heating and cooling

August 28, 2015

Smart temperature-control devices—such as thermostats that learn and adjust to pre-programmed temperatures—are poised to increase comfort and save energy in homes.

Smallest 3-D camera offers brain surgery innovation

August 28, 2015

To operate on the brain, doctors need to see fine details on a small scale. A tiny camera that could produce 3-D images from inside the brain would help surgeons see more intricacies of the tissue they are handling and lead ...

Team creates functional ultrathin solar cells

August 27, 2015

(Phys.org)—A team of researchers with Johannes Kepler University Linz in Austria has developed an ultrathin solar cell for use in lightweight and flexible applications. In their paper published in the journal Nature Materials, ...

Interactive tool lifts veil on the cost of nuclear energy

August 24, 2015

Despite the ever-changing landscape of energy economics, subject to the influence of new technologies and geopolitics, a new tool promises to root discussions about the cost of nuclear energy in hard evidence rather than ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.