The shark skin effect is the mechanism of wall friction reduction of a fluid due to a riblet structured surface. A new application for riblet surfaces may be jet engine blades. Riblet structured coatings on the blades would act as oxidation protection and additionally reduce the skin drag on the surface. In this study structuring surface areas of high temperature nickel-based alloys is investigated. These alloys are used for compressor and turbine blades near the combustion chamber. Experiments are performed by depositing titanium on a nickel base alloy through particular metal grids using magnetron sputtering. For single-digit micrometer structures, photolithography with subsequent electrodeposition of nickel as well as sputter deposition and thermal evaporation of several materials are investigated. Successfully fabricated structures are oxidized at 900-1000 deg C for up to 100 h and the resulting shape is characterized using scanning electron microscopy. The most accurate structures are obtained using photolithography and subsequent electrodeposition. The reduction of the wall shear stress was measured in an oil channel. The riblet structures prior to oxidation show a reduction of the wall shear stress of up to 4.9%.
Shark skin inspired riblet coatings for aerodynamically optimized high temperature applications in aeroengines
Haihautähnliche Rippenbeschichtungen für aerodynamisch optimierte Hochtemperaturanwendungen in Flugmotoren
Advanced Engineering Materials ; 13 , 4 ; 288-295
2011
8 Seiten, 9 Bilder, 24 Quellen
Article (Journal)
English
Research progress in high temperature functional coatings for advanced aeroengines
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