Summary

A third-order accurate, upwind-biased, thin-layer Navier-Stokes zonal code (STAGE-2) has been used to investigate stator clocking in a multistage compressor. The effects of stator clocking on the unsteady flow within a low-speed þstage compressor have been investigated. The results indicate that clocking in multistage compressors is a complex, non-linear phenomenon which warrants further study. In particular,

• Variations in efficiency, force amplitudes and frequencies are functions of the relative position of the clocked airfoil and convected wake groupings.
• The optimal combination of high efficiency and low force amplitude occured when the stator-1 wake convected along the pressure surface of stator-2.
• A slight movement of the stator-1 wake to the suction surface of stator-2 resulted in a distinct loss in efficiency and higher amplitude unsteadiness.
• When performing parametric studies of airfoil clocking, one must be careful in choosing the parameter variation in order not to overlook these effects.