Unsteady Off-Design Velocity and ReynoldsStresses in an Axial Compressor

Abstract

The aim of the present work is to provide unsteady experimental data about the flow in a one-stage axial compressor. Some particular flow features are described and discussed. The operating conditions considered here concern an off-design point that is dose to the compressor rotating stall limit. Measurements were performed with a three-dimensional laser Doppler velocimeter. Twenty-eight axial sections were surveyed from the rotor inlet to the stator outlet. In each section, velocity and velocity fluctuation measurements concerned more than 250 points. Thus, more than 8000 locations of measurement were investigated in the rotating and in the fixed parts of the stage. The main flow patterns associated with the rotor unsteadiness are described through a few pictures of the measured velocity components and of the Reynolds-stress distributions. Obviously, the most outstanding flow phenomena occur in the upper part of the rotor channels and take place along the stator blades suction side. In the moving row, secondary complex flow structures are highlighted, and the structure of the separated flow along the stator blade is analyzed.