Unsteady Flow Within Centrifugal Compressor Channels Under Rotating Stall and Surge

Unsteady flow patterns throughtout a centrifugal compressor system during the rotating stall and the surge were measured experimentally. Various kinds of unsteady behavior of the flow appeared both continuously and suddenly as the flow rate decreased. The part-span stall, the full-span stall, the mild and deep stalls, and the dep surge appeared clearly. The fluctuations caused by the full-span stall were seen even during surge and affected the flow within the scroll through the vaneless diffuser. The experimental results were compared with those computed by the lumped parameter theory