Unsteady flow surges that occur at low flow rates in compression systems, including turbo compressors, must be avoided because they can damage the compression system. In this study, the outlet plenum pressure of a small-flow centrifugal compressor was measured in detail and the precursor phenomena of surges were experimentally investigated. These results showed that small flow fluctuations occur and disappear repeatedly near the stable-unstable boundary of the internal flow in the compressors system. It seems that these flow fluctuations appear as a precursor of the surge.
HAGINO et al. (Wed,) studied this question.