Exit Flowfield of an Embedded Stator in a Multistage Axial Flow Compressor

Abstract

A complete area traverse downstream of the second stator of the Pennsylvania State University Multistage Compressor Facility has been carried out at the peak efŽ ciency and peak pressure ratio operating conditions using a miniature (1.07-mm-diam) Ž ve-hole probe and a thermocouple probe. Axial velocity, total pressure, and total temperature contours are presented and discussed at both operating conditions. Blade-to-blade proŽ les of total velocity and absolute  ow angle presented at three representative radii show the effect of loading on the wake structure between the two operating conditions. The stator clearance  ow and hub rotation result in  ow underturning (from design), which persists up to 10% of the span from the hub. A region of low  uid momentum develops on the suction side of the stator blade endwall (casing region) corner at both operating conditions. The low  uid momentum region in the suction side casing endwall corner is identiŽ ed as the dominant source of  ow unsteadiness to the downstream rotor at both compressor operating conditions. This is seen in the distribution of apparent stresses, which are conŽ ned to the wake region along most of the span, with the exception of the low  uid momentum core in the endwall region where signiŽ cant levels are reached across a substantial portion of the passage at both operating conditions.