Certainty and Interpretation of Inlet Stall Inception Position Caused By Volute Tongue in a Centrifugal Compressor

To determine the formation reason for the stall inception in a centrifugal compressor and analyze the relationship between the volute tongue and the stall inception position, the stall characteristics of a high-speed and small-flow centrifugal compressor was numerically investigated. The results indicate that the spike-type stall in this centrifugal compressor occurs as the flow structure changes during stall process. The stall inception is induced by the volute tongue blocking effect which results in the high pressure area at about 55° circumferential position of the volute. The pressure disturbance-wave adversely propagates to the impeller inlet through the forward inclined and backward swept passage, and the spike-type stall appears at about 115° circumferential position.