Abstract
The operating range of a centrifugal compressor is usually limited by the choke and the surge. The surge is related to the compressor system but it deeply relates to the inlet stall of impeller and/or the diffuser stall. Here, the velocity distribution in the inlet of a centrifugal impeller was measured using a dynamic PIV system to clarify the stall area at the impeller inlet. The correlations between the swirl flow and the reverse flow were discussed using a stereoscopic PIV system at three typical operating flows such as a stabile flow, an unstable flow and a full stall flow. As a result, the swirl flow appeared with decrease in flow rate owing to the reverse flow in a stall cell.
