UNSTEADY TOTAL PRESSURE FIELD DOWNSTREAM OF AN EMBEDDED STATOR IN A MULTISTAGE AXIAL-FLOW COMPRESSOR

The results from measurements of the unsteady total pressure field dow nstream of an embedded stage of a three stage axial flow compressor al e presented in this paper. The measurements include area traverses of a high response kulite total pressure probe and a pneumatic Jive hole probe downstream of stator 2 at the peak efficient operating point for the compressor. These data indicate that both the shaft-resolved and unresolved fluctuations contribute to the unsteadiness of the total pr essure field in multistage compressors. Specifically, regions associat ed with high levels of unsteadiness and consequently, high levels of m ixing including both the hub and casing endwalls and the airfoil wakes have significant levels of shaft resolved and unresolved unsteadiness . Temporal variations of stator exit pow are influenced by both shaft resolved and unresolved unsteadiness distributions. The limitations of state-of-the-art instrumentation for making measurements in moderate and high speed turbomachinery and the decomposition used to analyze th ese data are also discussed.