3DCeraTurb: Design and manufacture of CMC stator guide vanes for high-pressure turbines

Kurzfassung

Increasing the performance and efficiency of aero engines is essential for more environmentally friendly air transport. Rising temperatures, especially for combustion section and turbine structures, as well as lower weight of the components are key requirements for new materials. Together with adapted environmental coating systems and cooling features, ceramic composites are good candidates for aircraft applications. They are capable of withstanding high temperatures in an aggressive environment, while the density is two-thirds lower than conventional nickel-based alloys. As part of the DLR project “3DCeraTurb”, the Institute of Structures and Design and the Institute of Materials Research, along with several other DLR institutes, are developing turbine guide vanes made of silicon carbide fibre-reinforced silicon carbide composites (SiC/SiC CMC) and all-oxide CMC, respectively. One aim of 3DCeraTurb is to design and manufacture ceramic stator guide vanes for a high-pressure turbine, to experimentally investigate the vane behaviour in a wind tunnel and to evaluate performance, damage and lifetime for later application in an aircraft engine. The focus is the enhancement of the respective manufacturing processes from plate dimensions to more complex three-dimensional components. A ceramic-based design is the basis for the development and manufacture of a new guide vane geometry, taking into consideration material- and manufacturing-specific constraints. The manufacturing and development processes of the SiC/SiC and oxide CMC components will be presented with a particular focus on SiC/SiC. The SiC/SiC fabrication starts with the draping and CVI fibre coating of woven fabrics, followed by resin infiltration via resin transfer moulding. The final steps involve pyrolysis and liquid silicon infiltration. Surface grinding and laser drilling of cooling holes in the trailing edge are challenging parts during the final machining of the vanes. CFD simulations connected to FEM simulations are carried out accompanying the design and manufacturing process. The safety factors for the wind tunnel and the cruise load case are calculated using the Tsai-Wu criterion.