Drag-reducing paints for the reduction of fuel consumption in aviation and shipping

In October 2009 the European Commission decided that fuel consumption by aviation and shipping has to be reduced by 10% and 20% respectively by 2020.A significant contribution to this challenging goal could be a coating that reduces drag.For about 20 years it has been known that special microstructures (“riblets”) can lower drag by up to 10%. A new process for the production of such microstructured coatings on large surfaces is presented in this article. This process allows coating application, embossing, and partial curing in a single step. The coating material consists of VOC-free nanocomposites that give the coating the necessary abrasion resistance and weathering stability.Drag measurements have been carried out in a ship model basin and in a wind-tunnel respectively. In these experiments, smooth coatings were compared to riblet-structured coatings. These structures were adapted to the flow-parameters of the fluid. A surface-drag reduction of 5.2% for a torpedo-shaped specimen was measured in a large hydrodynamic and cavitation tunnel. In a wind-tunnel experiment a reduction of the total drag of a wing-profile by 6.2% was measured.Both experiments indicate the high potential for fuel savings in the transportation sector.