| Abstract | The Small Compressor Research Program is a co-operative project between the National Research Council of Canada (NRC) and Rolls Royce (Canada) Limited (RR). Its objectives are to investigate, both analytically and experimentally, the “Fanstat” concept of compressor spooling. This concept involves the co-rotation of both rotor and stator rows of a compressor in the core engine, with the fan being mounted on, and driven by, the rotating stator case. The primary function of the Fanstat is to provide an “aerodynamic gearbox” that will permit the fan and the fan turbine to run close to their individual optimum speeds, so overcoming the mismatch in blade speeds inherent in direct-coupled fan-turbine spools of high-bypass ratio turbofan engines.
Previous reports have described preliminary experimental calibrations of the conventional three-stage axial compressor from which the Fanstat compressor was derived, and a hybrid-computer model of the rotating stator compressor test rig. The current report describes a more-detailed calibration of this conventional compressor and presents the performance characteristics of the co-rotating compressor configuration.
The test results confirmed aerodynamic feasibility of the Fanstat arrangement of compressor spooling, and major performance parameters were not significantly different from the conventional compressor in the useful operating region. Flow range and surge behaviour of the co-rotating compressor were examined and, although somewhat unusual at various speeds, did not indicate any serious limitations on the applicability of the concept.
In general, the performance characteristics of the experimental Fanstat compressor substantiated the predictions of the hybrid-computer model and thus confirmed the latter as a useful and powerful tool for investigating the behaviour of this novel compressor arrangement. |
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