Experimental investigation for the effects of different unsteady source in centrifugal compressor

Experimental investigation on the unsteady flow in the vaned diffuser of a centrifugal compressor stage was performed. Detailed instantaneous flow has been measured at several different measuring positions using a hot-wire anemometer with the phase-locked ensemble-averaged technique. Different unsteady source are distinguished by circumferential-averaged technique and 'inverse spectral analysis'. The effects of different unsteady source on the flowfield and mechanism of the unsteady interaction are analyzed and explored. The results show that the repercussion effect of vaned diffuser is of the same order with the unsteadiness induced by impeller, while the repercussion effect of vaned diffuser is smaller. The repercussion effect of vaned diffuser and the unsteadiness induced by impeller decrease along the stream wise direction, and the gap between them also reduces along this direction. The unsteady effect of impeller is sensitive to the location of diffuser vane in radial gap, and it is larger near the convexity surface of the diffuser vane. The uncertain unsteady dimensionless velocity in radial gap is influenced by the repercussion effect of vaned diffuser insignificantly.