SINOPSIS

In modern gas turbine combustors a considerable contribution to the heat load of the liner arises from radiation. Under typical operating conditions, the radiative heat transer in the combustor is strongly affected by the interaction between the flame and the combustor walls. In this context, the radiative properties of soot, the combustion gases and the liner materials are of predominant importance.
In order to provide a proper understanding of these effects, the radiative interchange of a model gas turbine combustor has been investigated using a 2-D (cylinder-symmetric) numerical code. Unlike other approaches, the computation of radiative transfer was carried out spectrally using models that have been recently developed at the Institut für Thermische Strömungsmaschinen (ITS), Universität Karlsruhe. Besides detailed representation of the radiative properties of the liner materials, special emphasis was put on spectral modelling of the radiative properties of soot and the combustion gases.
The analysis shows, that the presence of soot is of major importance and that a significant reduction of the liner heat load can be achieved by thermal barrier coatings like ZrO₂. However, these coatings are very critical in case of abrasion leading to an extremely high radiative heat load to the uncovered metallic carrier material beneath the coating.