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- In-stall characteristics from high-speed post-stall transients are determined. The transient, surge-cycle nature of high-speed post-stall operation precludes the possibility of obtaining in-stall characteristics in a steady-state manner, as is possible during low-speed post-stall operation, which is characterized by quasi-steady rotating-stall behavior. Maximum likelihood parameter estimation techniques were used to obtain the quasi-steady high-speed characteristics from transient data. The necessary data was first obtained from a specially instrumented compressor that was tested well beyond its limits of normal operation. The unsteady, post-stall data thus obtained was then digitized and processed through a simplified analytical model to construct the input-output relationship necessary for estimation. In-stall characteristics were determined using this estimation procedure at two different high-speed conditions, 90 and 98.5 percent corrected speed. The estimated characteristics were found to be robust in the presence of measurement noise and unmodelled system dynamics, but the compressor response-time constants, also estimated, were more sensitive to these same disturbances. The experimentally determined low-speed in-stall characteristics and the estimated high-speed in-stall characteristics were then incorporated into a one-dimensional compressor simulation model developed as a parallel effort to the compressor testing and data reduction effort, which yielded predictable results.
- Document ID: 19880019545.
Accession ID: 88N28929.
- No Copyright.
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