The wave rotor is a turbomachinery component that accomplishes the compression and expansion processes of a high-pressure spool (i.e., a gas generator or gasifier) within a single component. It is self-cooling and aerodynamically compatible with the low corrected flow rates supplied by the compressors of modern, high-pressure-ratio turboshaft engines. A wave rotor can be embedded concentrically between the high-pressure compressor and high-pressure turbine to increase the overall pressure ratio of the gas turbine engine by a factor of three and increase the peak temperature by 25 percent, without increasing the temperatures of the rotating machinery components. These thermodynamic increases enhance gas turbine engine power and efficiency significantly. For example, the wave rotor is predicted to increase the specific power of the Rolls-Royce Allison model 250 helicopter engine by 18 percent while reducing specific fuel consumption by 15 percent.
Four-port wave rotor test rig.
A four-port wave-rotor component (see the photo) that could be used to top future advanced gas turbine engines was successfully tested at the NASA Glenn Research Center at Lewis Field in this past year. This series of experiments established the first operating map for a four-port throughflow wave rotor, marking a major milestone for Glenn’s wave rotor project. The wave-rotor pressure ratio—a measure of performance—was found to be a function of corrected heat addition, corrected flow, and corrected rotor speed, in qualitative agreement with numerical predictions from in-house computational fluid dynamics (CFD) codes. The performance levels were lower than anticipated, and this has been attributed to augmented heat transfer between the rotor and the working fluid. The in-house CFD tool for wave-rotor design and analysis was improved and further validated with the on- and off-design data generated during the experiments. The wave-rotor operating map and the validated CFD tool are key to future wave rotor technology development.
Progress toward the planned demonstration of a four-port wave rotor within a small turboshaft engine was made in the past year under a contracted effort with Rolls-Royce Allison. Previous work included a preliminary design and general layout of the wave-rotor-topped engine, a detailed cycle analysis that established the predicted performance levels of the demonstrator engine, and a successful aerodynamic design of low-loss transition ducts for porting hot gases from the wave rotor to the high-pressure turbine. In the past year, the mechanical design of the rotor portion of the wave rotor was initiated. The work includes preliminary design and detailed heat transfer, stress, and structural dynamics analyses.
Glenn contact: Dr. Gerard E. Welch, (216) 433–8003, Gerard.E.Welch@grc.nasa.gov
Authors: Dr. Gerard E. Welch, Dr. Jack Wilson, and Dr. Daniel E. Paxson
Headquarters program office: OAST
Programs/Projects: Propulsion R&T
Last updated April 24, 2000, by Nancy.L.Obryan@nasa.gov
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