Asymmetry of rotor tip clearance in compressors always exists to some extent.To investigate the effects of rotor tip clearance asymmetry on compressor performances

a series of nonaxisymmetric tip clearance casing configurations were designed and experimented on a low speed

axial flow compressor with a single rotor.For each geometry

experiments were taken under both 5059 r/min and 8130 r/min conversion velocities.According to the experiments

several phenomena could be obtained:(1) With tip clearance asymmetry increasing

the stall points on compressor performance curves shifted to the lower right

compared with the solid casing and symmetric tip clearance.To evaluate such shifting effects quantitatively

two parameters were defined.(2) With tip clearance asymmetry increasing

the average stall performance was also decreased.(3) On the other hand

however

the size of the stall-unstall hysteresis loops on the performance map decreased with the increasing of the tip clearance asymmetry

which showed that it was easier for the compressor to recover from stall.As a whole

the experimental results showed that

such treated casings were detrimental to the compressor performances.