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2267 |
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Monday, May 03, 2010, Hullet Room 10:30 AM Gas Turbines 1 |
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Composite coatings with drag reduction and self cleaning properties |
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Viktor Drescher* / Berlin Institute of Technology
Sekr. PTZ 6, Germany Johannes Wilden / TU Berlin, Germany P. Schaaf/ TU Ilmenau, Germany |
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Today, the efficiency of turbines is limited by different losses. Minimizing these losses is a main goal to reduce fuel consumption and produce more environmentally friendly machines. Observations on the scales of fast swimming sharks display a riblet structure. These riblets provide a significant reduction of drag losses, but are quite sensitive on pollution. Therefore, for a good performance, it is essential to combine these structures with self-cleaning properties. A lateral- and depth-selective distribution of particles with a negative thermal expansion coefficient in a binder with positive thermal expansion coefficient can be used to deform the surfaces depending on the temperature. At high temperatures (e.g. in flight) a riblet structure will be formed by local expansion or shrinkage and at cooling down the surface will be cleaned by the reversal of the deformation. Beside the production of a coating with a lateral- and depth-selective distribution of the NTE-ceramics within the binder the thermodynamical stability of the ceramics inside the binder is part of the investigations to provide a sufficient long-time stability of the coating. |