Study on physical mechanism of partial surge

Partial surge is a type of flow phenomena found in transonic axial compressor, which has similar characteristics as surge. To figure out the physical origin of partial surge could enrich transonic compressor instability theory, and it could be important to enlarge the mass flow range of transonic compressor. To solve this problem, based on Greitzer's B parameter modal, experimental investigations are carried out. Inlet ducts with different length are mounted to change B factor of the system. Experimental data is analyzed by both time domain and frequency domain to analyze instability evolutions. The results indicate that: (1) as the B factor is 0.39, partial surge does not occur, while surge occurs in the end of the procedure. (2) As the B factor is 0.51, partial surge could lead into surge turning the compressor into instability. (3) As the B factor is 0.7, partial surge could lead into rotating stall cells at rotor tip region. Therefore, partial surge is a type of instability precursor, which could lead into not only rotating stall cells but also direct surge.