The time-average and unsteady static pressure fields, and the velocity field were measured in a rotor-stator disk cavity and its main-stream gas path. Ingestion of main gas into the disk cavity was also measured. Some CFD simulations were performed. The time-average static pressure was circumferentially periodic (following the vane pitch) in the main-stream gas path and circumferentially uniform in the cavity. The unsteady pressure in the stationary frame of reference was periodic, following the passing of rotor blades, both in the main gas path and in the disk cavity. In the main gas path, the circumferential asymmetry amplitude of the time-average static pressure and the pressure unsteadiness amplitude were of the same order of magnitude. Steady CFD simulations were unable to predict ingestion in the cases where ingestion was detected by tracer gas measurement. It appears that simulations will need to be unsteady as well as three-dimensional to be able to predict ingestion correctly.

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