High Temperature Turbine Technology Research Articles

Development, Fabrication, and Testing of a Prototype Water-Cooled Gas Turbine Nozzle

The design and development of a water-cooled high temperature gas turbine has been under active investigation by the General Electric Gas Turbine Division for the past 15 years. The transition from testing small scale, laboratory-size experimental hardware to full scale industrial gas turbine components was initiated in 1975 by General Electric and extended further under the U.S. Department of Energy’s High Temperature Turbine Technology (HTTT) program. A key element in this transition was the identification of a composite (hybrid) design for the first stage nozzles. This design permits efficient heat transfer to the water-cooling passageways, thus lowering effective strains and increasing part life. This paper describes the metallurgical considerations and process technology required for such hardware. A review of the materials selection criteria utilized for the nozzle is presented, along with the results of several materials development programs aimed at determining metallurgical compatibility of the component materials, diffusion bonding behavior and both hot corrosion and aqueous corrosion performance of key materials. A brief description of the actual cascade testing of the part is given, along with results of a post-test metallurgical analysis of the tested hardware.

Water-Cooled Gas Turbine Monometallic Nozzle Fabrication and Testing

This paper describes the fabrication and testing of the second-stage monometallic water-cooled nozzles for the Department of Energy funded High-Temperature Turbine Technology (HTTT) program. The materials and processes development work required to fabricate these nozzles has been reported in an earlier paper. The fabrication of these nozzles—including investment casting, Shaped Tube Electrolytic Machining (STEM), Electrode discharge Machining (EDM), conventional machining, and brazing—is described. The testing of these nozzles in a static hot-gas path development test stand is also described, and the results of this testing are discussed in terms of the overall component design goals.

Comparison of the HTTT Reheat-Gas-Turbine Combined Cycle With the HTTT Nonreheat Gas-Turbine Combined Cycle

High-temperature turbine technology (HTTT) when applied to the reheat-gas-turbine combined cycle (RHGT/CC) offers distinct advantages over the presently contemplated United States Department of Energy (DOE) HTTT simple-cycle gas-turbine combined cycle (SCGT/CC) being developed for gaseous fuel derived from coal. Specific improvements are: 1) higher combined-cycle efficiency, 2) higher specific output per unit of air flow, 3) less critical high-temperature nozzle-vane and rotating-blade surface area to be cooled, 4) less strategic high temperature metal material to be used, and 5) less overall cycle-cooling degradation allowing growth potential. New cooling techniques employing steam are required to accomplish these projections which necessitates advanced research and development and presently unavailable mathematical analytical approaches.

Water-Cooled Gas Turbine Monometallic Nozzle Development

This paper describes the materials and processes development required to fabricate the second stage monometallic water-cooled nozzle for the Department of Energy funded High Temperature Turbine Technology (HTTT) program. Materials engineering and development work including alloy selection, hot isostatic pressing (HIP), and heat treat optimization necessary to fabricate this component is described and the results of this work are reported. Specialized processes utilized to achieve tight design tolerances such as TRW’s split mold investment casting and shaped tube electrode machining (STEM) are also described. The advantages of these processes are discussed in terms of the overall component design goals.