The aim of the project „Brennkammer 2000“, with 4 DLR Institutes working together in close cooperation, is the development of highly efficient, low emission jet engines for future aircraft. This should be reached with new burner technologies and turbine input temperatures of up to 2000 K in combination with reduced consumption of cooling air. Therefore new combustion chamber liners, based on high temperature resistant, oxide and nonoxide Ceramic Matrix Composites (CMC), such as WHIPOX (Wound Highly Porous Oxide Composite) or SiC/SiC materials, are required.
Within the framework of the project, WHIPOX combustion chamber shingles are designed, manufactured and tested at realistic conditions.
The main emphasis of our work is on the integration of the shingles in the combustion chamber. Therefore the differences in service temperatures as well as of the coefficients of thermal expansion between the CMC components and the metallic support structure have to be taken into account carefully. With a newly developed joining concept, based on a ring structure, built up by assembling individual shingles, a reliable and stress free integration can be obtained independently from temperature.
The potential of WHIPOX materials in this highly demanding application will be investigated on flat, effusion cooled combustion chamber shingles by the DLR Institute of Propulsion Technology.
Whereas the DLR Institute of Material Research, Cologne, is responsible for the material development as well as for the manufacture of the WHIPOX shingles, the DLR Institute of Structure and Design, Stuttgart, is focused on the design, layout and dimensioning of the combustion chamber shingles on the basis of realistic loads and environmental conditions. Thereby, the temperatures in the shingles are calculated via CFD (Computational Fluid Dynamics) simulations and integrated into the FEM analysis, with which the induced inner stresses of the combustion chamber shingles can be determined. In an iterative process, the consumption of cooling air can be reduced by varying the cooling configurations, while keeping the induced stresses at an acceptable level.
Additionally, a quality assurance system for WHIPOX combustion chamber shingles will be built up as a basis for the future introduction in real engines. Thereby destructive as well as non destructive evaluation methods, such as air and water coupled ultrasound, X-ray computertomography, lock-in thermography and photogrammetry, will be investigated and adapted to the CMC materials and components.