A novel centrifugal gas turbine design was developed and prototype tested. The research effort consisted of the design, development, and full prototype testing of a 50 HP centrifugal gas turbine. The novelty of the centrifugal gas turbine concept is that it is based on a radial flow gas turbine consisting of a centrifugal compressor and impulse turbine mounted on the same side of a rotating wheel. The radial flow-vaned combustor is mounted on the wheel’s stationary shroud; consequently, there is no 180-degree flow turning required as in conventional radial flow gas turbines. This very simple and rugged gas turbine concept has the following major advantages: • Single rotating component (i.e., mechanically simple and compact gas turbine). • Portability. • Short axial span. • High tolerance to injection of particulate matter. • Simple construction; low manufacturing costs. This project included the conceptual design, structural and aerodynamic analysis, performance prediction modeling, detailed design, prototype fabrication, test rig instrumentation, compressor/turbine characterization, rotordynamic signature, combustor design, combustor testing, controls implementation, light-off testing, no-load testing, and performance testing of the gas turbine. Design analyses that were performed included 1-D thermodynamics, finite element structural and thermal, rotordynamic, 2-D blade path optimization, and 3-D Computational Fluid Dynamics (CFD). Testing of all individual gas turbine elements (compressor, combustor, and turbine) as well as the entire assembly was completed. Tests showed that stable gas turbine combustion was achieved up to 26,000 RPM. The gas turbine reached self-sustaining power at 21,000 RPM and 405°C firing temperature. Thus, the centrifugal gas turbine concept was demonstrated to function properly and to achieve positive power output. However, the design output power was not achieved because of combustion stability range limitations at speeds above 20,000 RPM. Maximum output power achieved was 1.4 kW at 23,000 RPM. Recommendations are provided to overcome these operational limitations in the next model centrifugal gas turbine.

A centrifugal gas turbine is developed based on a straight radial flow design with no axial flow turning. The geometry contains only two major elements — a rotor disk and a stator shroud. The rotor consists of a centrifugal compressor and high impulse radial outward-flow turbine connected to an electric generator. The stator shroud contains the combustor and nozzles. Fuel lines are attached to the shroud, ducted directly into the combustor. The difference between this novel design and conventional radial gas turbine is that the compressor and turbine section are installed on the same side of the rotating wheel, while the combustor and nozzle are mounted on the stationary shroud. Thus, the entire assembly consists of two components. Technical advantages are: • Single Rotating Component; • Short Axial Span; • Compact Two-Piece Construction; • Ease of Maintenance/Repair Access. Aerodynamic design, performance, and structural analysis of this design are discussed.

A prototype of a novel gas turbine concept is being developed to demonstrate the technical feasibility of a gas turbine design based on a straight radial flow with no axial flow turning. The prototype gas turbine consists of only two structural elements — a rotor disk and a stator shroud. The rotor consists of a centrifugal compressor and high impulse radial outward-flow turbine connected to an electric generator. The stator shroud contains the combustor and nozzles. The difference between this novel design and conventional radial gas turbine is that the compressor and turbine section are installed on the same side of the rotating wheel, while the combustor and nozzle are mounted on the stationary shroud. Thus, the entire assembly consists of two components. Technical advantages are: • Single Rotating Disk; • Compact Two-Piece Construction; • Ease of Repair and Maintenance; • High Power to Weight Ratio. This paper discusses the test set-up, instrumentation, and initial mechanical testing of the radial gas turbine. Performance predictions, rotordynamics analysis, and aerodynamic component verification are also discussed.

A prototype of a novel gas turbine concept is being developed to demonstrate the technical feasibility of a gas turbine design based on a straight radial flow with no axial flow turning. The prototype gas turbine consists of only two structural elements—a rotor disk and a stator shroud. The rotor consists of a centrifugal compressor and high impulse radial outward-flow turbine connected to an electric generator. The stator shroud contains the combustor and nozzles. The difference between this novel design and conventional radial gas turbine that the compressor and turbine section are installed on the same side of the rotating wheel, while the combustor and nozzle are mounted on the stationary shroud. Thus, the entire assembly consists of two components. Technical advantages are: • Single Rotating Disk; • Compact Two-Piece Construction; • Ease of Repair and Maintenance; • High Power to Weight Ratio. This paper discusses the combustor development and preparation for design testing of the prototype radial gas turbine.