The nature of wakes in multistage axial flow compressors

This paper describes the measurement and processing of unsteady turbulence data from a multistage low-speed compressor. In this study, a two-element hot-wire probe was traversed along a circumferential path downstream of the third rotor row of a large-scale low-speed four-stage facility. Simultaneous circumferential and axial velocity measurements were made. Three flow conditions were measured: peak efficiency with blade Re = 200 000, peak efficiency with blade Re = 55 000 and close to stall with blade Re = 200 000. Ensemble averaging has been used to deduce the periodic components of the velocity. In addition, measurements have been made of turbulence intensity, turbulence length scale and turbulent shear stress (Reynolds stress).