Abstract
This paper describes a method that enables the identification of compressor characteristics in parts that cannot be measured in traditional core test procedures. This capability is expected to help in identifying needed design changes following core tests. The method uses measurements of the mass flow rate in the compressor inlet along with the plenum pressure to infer the equilibrium characteristic of the compressor even as the compressor experiences non-equilibrium conditions, particularly so during transients to stall. A throttle control with feedback from the measured mass flow rate is used to drive the compressor into growing oscillations around the stability boundary, and a dynamic correction method is used to collapse the growing oscillations into a single line on the compressor map, which estimates the equilibrium characteristic. An unsteady mean line compressor flow model that is capable of capturing acoustic waves propagating through the rotor and stator blade cascades is used as a test compressor to evaluate the method. Results obtained using simulated compressor flow transient data demonstrate that the proposed identification method estimates both the smooth and the non-smooth characteristics with satisfactory accuracy.
