Posting in Energy
German researchers develop a paint that mimics the aerodynamics of shark scales. Could this mean smoother sailing for ships, soaring for planes, and spinning for wind turbines?
A few weeks ago, I wrote about bionic cargo ships, inspired by a hydrophobic fern, that would decrease a ship's drag as it cruises through the ocean. In another effort to make surfaces slicker, researchers from the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research (IFAM) are looking to sharks.
The ridged scales of sharks reduce friction between the animals and their watery surroundings. This helps sharks to swim swiftly and silently through the water. In short bursts, some sharks can reach more than 30 miles per hour with little effort.
Known as the "riblet effect," the hydrodynamic* advantage sharkskin may provide to seafaring vessels might also reduce resistance for objects gliding through the air, such as airplanes or the blades of windmills. [*edit]
German researchers have developed a paint that mimics the dermal dentricles, or placoid scales, of fast-swimming sharks. According to the scientists, the coating covers 3-dimensional surfaces easily and reduced friction by more than 5 percent in tests at a ship construction facility. Container ships transport about 90 percent of global trade from port to port and are big, heavy and huge fuel guzzlers. Over the course of a year, one large cargo ship could potentially save 2,000 tons of fuel.
Of course, there are some lifestyle differences between a shark and an airplane, a turbine, and a boat. So nanoparticles within the paint allow it to withstand ultra-violet radiation, temperature fluctuations (between -67 and 158 degrees Fahrenheit), and mechanical loads.
Volkmar Stenzel in a statement:
Paint offers more advantages. It is applied as the outermost coating on the plane, so that no other layer of material is required. It adds no additional weight, and even when the airplane is stripped – about every five years, the paint has to be completely removed and reapplied – no additional costs are incurred.
By applying the paint to a plane via a stencil, the surface achieves the correct texture.
The next step for the researchers? Determining how to keep barnacles and algae from gumming on to ship hulls and gumming up the vessel's fuel efficiency.
Image 1: Flickr/Alfonsator
Image 2: NASA
May 24, 2010
As long as the top of the wing is painted with or without painting the underside of the wing, the lift should be maintained. Some aircraft have used a slightly different twist on this in the form of laminar airflow, over the top surface of the wing. The only real problem (I can recall) of decreasing turbulence over the upper surface occurs when the technology is defeated by environmental factors like ice on the wings. This problem has resulted in few aircraft falling out of the sky. Laminar air flow was employed (still is) on fighter aircraft. I would guess that the military is already testing sharkskin paint. What does this technical advance promise us in the fashion world, I wonder? Will we return to wearing shark skin suits? Will we be better able to withstand wind while being fashionably dressed at the same time? What color tie goes well with a shark skin suit? How silly will aircraft look wearing ties? Why do so many readers attack Melissa and other writers over word choices like aerodynamics vs. hydrodynamics vs. fluid dynamics? I found the article interesting and informative. Kudos to Melissa. Kudos as well to wizoddg for expanding my horizons about fluid dynamics.
Yes, words do have meaning, but aerodynamics and hydrodynamics are both just subsets of fluid dynamics, and there is no difference in the math. Only the density of the fluids vary.
why they don't coat airplanes (or racecars for that matter), with the same stuff that's on the outside of golf balls.
Why not coat the underside of wings? Do you fear that it would reduce lift? Don't fear, my friend. Lift on a wing is not related to friction at all. It depends only in the difference in distance the air have to travel between going over or under the wing, and the speed of the wing through the air.
Why don't they use the lotus leaf technique that other researchers have shown which doesnt even let the water touch the surface, surely that would solve all problems.
Airbus did try riblets skins in the 1980s. In 1987, the winner of the America's Cup had riblet skins. So its hardly news! The problem is maintenance. You can't keep the nanocracks clean of fouling and algaes, or of the normal dust and insects on airplanes. Only operational constraints decide when an invention is ripe to use... D. Charles