Of the four key technology areas attendant to the automotive gas turbine (ACT), structural ceramic components are the prime focus of the Department of Energy (DOE)-sponsored, NASA-managed ATTAP. The General Motors (GM) ATTAP team first focused on the ceramic gasifier turbine rotor, and in 1990 achieved full design temperature (2500°F TIT) at 100%N1 (gasifier speed). Four generations of axial-rotor design have led to such success, which also includes demonstrated resistance to foreign object impact; functionality after impact and minor damage; survivability in high-speed tip rub; and a 1000-hour durability demonstration. The ceramic gasifier turbine static structure, comprising scroll and vaneset (plus other support components), has also been successfully demonstrated at full (2500°F) design conditions, including successful completion of a 100-hour durability test of an all-ceramic gasifier stage. This major contractual milestone was completed during 1991. These successes represent fundamental technology progress, not only in the GM designs, but in the materials and processes implemented by the Kyocera Corporation, Norton/TRW Ceramics, and GTE Labs.
Heat management (regenerator system and thermal insulation) and combustion are other key AGT technologies. Ceramic regenerator disk efforts with Corning focus on developing extrusion technology in concert with evaluation of four ceramic material systems, to provide a disk with the requisite geometry, strength, survivability, and cost characteristics. Insulation activities with Manville target developing a ceramic refractory fiber-based system, which is wet injection molded directly in-place, and has the required thermal, adhesion, durability, and erosion properties. During 1991 a turbine engine component was successfully injection molded with this system. Some ATTAP effort has been directed toward design of a prevaporizing/premixing combustor to meet the California 0.2 gm/mile NOx standard.
Progress on the Advanced Turbine Technology Applications Project (ATTAP), and Automotive Gas Turbine Outlook