Three arc curve slot casing treatments that differ only in the number of treatment slots were utilized to investigate the influence of unsteady interaction frequency on the performance of the compressor.The experiment results indicate that the frequency of unsteady interaction between the arc curve casing treatment and the compressor

which represents the number of casing treatment due to the relative movement between rotor blades and treatment slots

should be tuned close to the vortex shedding frequency or within the range of lock-in frequency.The influence of casing treatment on the total pressure flow fields of the compressor stator were investigated utilizing total pressure rake

the experiment results indicate that the unsteady interaction between the compressor and the casing treatment should improve the separated flow field around the compressor

and which influence the radial distribution of the total pressure rise.