Investigation of the Tip Clearance Flow Inside and at the Exit of a Compressor Rotor Passage—Part I: Mean Velocity Field

This paper reports on an experimental study of the nature of the tip clearance flow in a moderately loaded compressor rotor. The measurements reported were obtained using a stationary two-sensor, hot-wire probe in combination with an ensemble averaging technique. The flow field was surveyed at various radial locations and at ten axial locations, four of which were inside the blade passage in the clearance region and the remaining six outside the passage. Variations of the mean flow properties in the tangential and the radial directions at various axial locations were derived from the data. Variation of leakage velocity at different axial stations and the annulus-wall boundary layer profiles from passage-averaged mean velocities were also estimated. The results indicate that there exists a region of strong interaction of the leakage flow with the annulus-wall boundary layer at half-chord. The profiles are well-behaved beyond this point. The rotor exit flow is found to be uniform beyond 3/4 blade chord downstream of the rotor trailing edge.