An enhanced compressor sub-idle map generation method

Several techniques have come about for the mathematical extrapolation of compressor maps from the idle region down to zero speed. Relatively little work has been done on methods which attempt to extract compressor sub - idle performance from physical grounds. This paper focuses on the design of an axial compressor rig to obtain sub - idle data in the form of locked rotor and windmill characteristics. The rig design is presented and the results obtained discussed. The data gathered is used to generate physics - based sub - idle compressor maps which are then compared to existing method s for sub - idle map generation. Interpolation from the locked rotor characteristic is shown to improve map generation over extrapolation methodologies, while the windmilling characteristic is shown to be an important addition to the interpolation process.