Abstract: The stall inception of a 2-stage low-speed axial compressor is investigated with uniform inlet flow. By installing high response dynamic pressure transducers in the circumferential, radial and axial directions, the dynamic pressure data at different positions are collected and analyzed using time analysis, frequency analysis and time-frequency analysis respectively. The results show that there is only one stall cell occupying the full span region, and that only modal wave type disturbance appears ahead of a rotating stall. The stall inception exhibits three-dimensional and unsteady characteristics. Both the modal wave disturbance and the stall cell form in a local position firstly, which will extend to other regions in the radial and axial directions soon after their appearance and finally occupy the whole span of all the rotors and stators.

Key words: compressor, stall inception, modal wave, three dimensional, unsteady