Under the ongoing DOE/NASA-funded Advanced Turbine Technology Applications Project (ATTAP), Garrett Auxiliary Power Division (GAPD) is continuing to address the issues of developing and applying structural ceramics to production gas turbine engines. Several critical technologies are being developed to advance this issue, including design methods development, component design, component fabrication, material characterization, and engine testing. The brittle nature of structural ceramics highlights concerns regarding impact damage. Through analysis and experimentation, design methods are being developed to improve the resistance of ceramic components to impact damage. Ceramic component designs now integrate these design methods into practice and proof testing methods are being developed to verify the results for actual engine components. Ceramic component fabrication processes are being optimized by selected subcontractors, resulting in deliveries of high-quality ceramic components which fully meet engine test needs. Verification of the component material properties is being achieved through comparisons of material property data from test bars cut from actual engine components with data generated from ceramic material test specimens. All these efforts are aimed at demonstrating endurance of the AGT101 all-ceramic turbine engine at the maximum operating temperature conditions up to 2500F (1371C).
These critical ceramics technologies being developed under ATTAP are also providing a critical launch pad into production-oriented programs. GAPD has three concurrent programs underway, aimed at integrating ceramics into production Auxiliary Power Units (APUs). These include: installing and evaluating ceramic turbine nozzles under actual field conditions in a well-established product line (the 85 Series Ceramic Nozzle Demonstration Program); incorporating ceramic first-stage turbine stators and blades in a three-stage axial turbine APU (the 331-200 Ceramic Demonstration Program); and incorporation of a ceramic first-stage turbine stator in our latest APU design, the G250 Auxiliary Power Generation System (APGS) for the USAF F-22 fighter aircraft.