Drastic changes occur in the physical properties of supercritical carbon dioxide (S-CO2) near the critical point

which easily induce phase change condensation inside the S-CO2 centrifugal compressor

which causes flow losses and blade erosion

thereby affecting the compressor's efficiency and service life. To ensure the safe operation of the centrifugal compressor

this study employs 3D full-channel numerical simulation. Based on the equilibrium phase change model and shear-stress transport (SST) k-ω turbulence model

and by integrating parameters such as temperature contours

pressure contours

velocity contours

leakage flow

and vortex structures

the source location

causes

and formation process of condensation are investigated. Additionally

a suppression method based on blade structure optimization is proposed. The results indicate that the acceleration at the impeller inlet induces condensation at the blade leading edge; a larger blade tip clearance forms leakage flow

which drives the movement of the low-pressure zone and triggers condensation in the blade tip clearance. Within one rotation cycle

the condensation distribution is related to the flow rate: condensation first appears in the blade tip region near the blade leading edge

and expands toward the blade hub as the flow rate increases; under low flow rate conditions

condensation only occurs at the leading edge. When the leading edge blade curvature is increased to 4

the condensation mass fraction at the leading edge decreases by 6%. After increasing the leading edge blade curvature

the condensation mass fraction decreases by 6%

the isentropic efficiency increases by 0.5%

and the pressure ratio increases by 0.012. The results provide a theoretical basis for the design optimization and safety improvement of centrifugal compressors.