Ceramic Strut Injection Technologies for High-Speed Flight

Abstract

Hypersonic airliners are exposed to temperatures that are beyond the limits of classical aircraft materials. In order to handle this problem the latest development of oxidation resistant materials and composite structures needs to be taken into account. The European research programs ATLLAS and ATLLAS II (2006-2014) were therefore focussing on advanced light-weight, high-temperature capable material development strongly linked to a high-speed passenger aircraft design. For propulsion components, combustor structures were investigated at academic level, both at basic and relevant environments. Within the frame of current work, injectors for ram-based propulsion concepts such as dual-mode ramjet or combined cycle concepts were analysed. Generic strut injector geometries were defined to investigate different materials (ceramic matrix composites and ultra high temperature ceramics) and cooling concepts (passive radiation-cooled vs. active transpiration-cooled). Ceramic strut injectors were designed, manufactured and tested within a high speed combustor at the industrial hypersonic METHYLE test facility. Tests were conducted at operational relevant conditions corresponding to a Mach 6 free flight. All injector variants successfully passed testing. It turned out that active transpiration-cooled CMC- and passive UHTC-solutions show the potential to ensure long range cruises of a high speed airliner.