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Shark Skin for High Temperature Applications - A Flow Optimized Protective Coating

Büttner, Claudia and Fröhlich, Maik and Schulz, Uwe (2008) Shark Skin for High Temperature Applications - A Flow Optimized Protective Coating. Junior Euromat, 2008-07-14 - 2008-07-18, Lausanne, Schweiz. (Unpublished)

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The high speed of sharks is caused by a reduced friction between water and skin due to a riblet structure on the skin surface. This effect has already been used for airfoil wings that were laminated with polymer films structured with riblets. A reduced flow resistance results in less fuel consumption. The challenge is to produce such a riblet structure on turbine blades to noticeably reduce the friction of flowing gas, leading to higher efficiencies of turbine engines. Theoretical considerations show that riblets on turbine blades need to be in the dimension of a few micrometers. This is smaller by an order of magnitude than structures on airfoil wings. The occurring Reynolds’ numbers, which determine the gas flow resistance and therefore the required structure dimensions on the surface, are much higher for turbine blades due to a higher velocity and pressure of the gas. In this study the suitability of some structuring methods on high temperature materials have been investigated. First experiments were performed by depositing titanium on a nickel base alloy through particular metal grids using magnetron sputtering. Furthermore, riblets in the micrometer range were successfully produced on a coating system by picosecond laser treatment. The ideal structured NiCoCrAlY coating deposited on nickel alloys substrate combines high oxidation resistance with low friction in a hot gas flow. This system was tested at 1000°C in air with regard to the stability of the formed structure. After oxidation for 100h the riblets are still intact. The structures were analysed prior and after exposure by using scanning electron microscopy.

Item URL in elib:https://elib.dlr.de/56284/
Document Type:Conference or Workshop Item (Speech, Poster)
Title:Shark Skin for High Temperature Applications - A Flow Optimized Protective Coating
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Date:14 July 2008
Refereed publication:No
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Keywords:High Temperature Materials, Protective Coating, Shark Skin, Structuring, Micrometer
Event Title:Junior Euromat
Event Location:Lausanne, Schweiz
Event Type:international Conference
Event Dates:2008-07-14 - 2008-07-18
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Propulsion Systems (old)
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Turbine Technologies (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > High Temperature and Functional Coatings
Deposited By: Büttner, Claudia
Deposited On:28 Nov 2008
Last Modified:27 Apr 2009 15:31

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