Unsteady Total Pressure Field Downstream of an Embedded Stator in a Multistage Axial Flow Compressor

Abstract

The results from measurements of the unsteady total pressure field downstream of an embedded stage of a three stage axial flow compressor are presented in this paper. The measurements include area traverses of a high response kulite total pressure probe and a pneumatic five hole probe downstream of stator 2 at the peak efficiency operating point for the compressor. These data indicate that both the shaft-resolved and unresolved fluctuations contribute to the unsteadiness of the total pressure field in multistage compressors. Specifically, regions associated with high levels of unsteadiness and, consequently, high levels of mixing including both the hub and casing end walls and the airfoil wakes have significant levels of shaft resolved and unresolved unsteadiness. Temporal variations of stator exit flow 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 these data are also discussed.