Wind Tunnel Testing at TRL4 of EBC Coated SiC/SiC Nozzle Guide Vanes for High-Pressure Turbines With Trailing Edge Cooling

In order to fulfill the high flight requirements for a significantly lower environmental impact, new approaches to the design of engines are required. One solution to build an engine as a whole more efficiently is the use of a non-oxide ceramic matrix composite (CMC) based on SiC-fibers in a SiC matrix (SiC/SiC) in the thermally most challenging part of the engine: The high-pressure turbine. The development of SiC/SiC CMCs presents a significant challenge, which we have addressed by producing a high-pressure turbine stator made of SiC/SiC CMC and coated with a newly developed environmental barrier coating (EBC). This advancement has elevated the development level of DLR SiC/SiC CMCs from TRL3 to TRL4. Part of this feasibility study is a test at TRL4 in the Wind Tunnel for Straight Cascades in Göttingen (EGG). The vane performance at different cooling flow ratios is analyzed. The EBC has a low roughness and therefore a nearly complete laminar boundary layer on the suction side with the transition observed near the trailing edge at subsonic flow. The transition location on the suction side was detected using an infrared camera and additionally with time-resolved temperature-sensitive paint (iTSP) at different Mach and Reynolds numbers.