Aspirating Probe Measurements of the Unsteady Total Temperature Field Downstream of an Embedded Stator in a Multistage Axial Flow Compressor

Abstract

The results from the area traverse measurements of the unsteady total temperature using a high-response aspirating probe downstream of the second stator of a three-stage axial flow compressor are presented. The measurements were conducted at the peak efficiency operating point. The unsteady total temperature data are resolved into deterministic and unresolved components. Hub and casing regions have high levels of unsteadiness and consequently high levels of mixing. These regions have significant levels of shaft resolved and unresolved unsteadiness. Comparisons are made between the total temperature and the total pressure data to examine the rotor 2 wake characteristics and the temporal variation of the stator exit flow. Isentropic efficiency calculations at the midpitch location show that there is about a 4 percent change in the algebraically averaged efficiency across the blades of the second rotor and if all the rotor 2 blades were behaving as a “best” blade, the improvement in efficiency would be about 1.3 percent. An attempt is made to create a composite flow field picture by correlating the unsteady velocity data with temperature and pressure data.