To fully understand the instability mechanism of highly load compressors

the occurrence mechanism of instability inception partial surge was studied in detail. Based on the experimental data of instability evolution at different rotation speeds and uniform intake of a transonic compressor

the instability evolution under inlet distortion was studied by experimental and numerical methods. The results show that under uniform intake

partial surge can only be detected at high rotation speed while at low rotation speed partial surge can't be detected. So it can be supposed that high blade loading at hub is related to the occurrence of partial surge. The results under different inlet condition suggest that lower blade loading in the hub region could prevent the occurrence of partial surge at high rotation speed while partial surge would occur at the low rotation speed if the blade loading in the hub region is higher. High blade loading in the hub is proved as a necessary condition for the occurrence of partial surge. In this compressor

if the diffusion factor exceeds 0.6 at near stall point

partial surge may occur.