ANALYSIS OF THE IMPELLER - VANED DIFFUSER INTERACTION IN A CENTRIFUGAL COMPRESSOR BY MEANS OF AN AERODYNAMIC FAST RESPONSE PROBE

As centrifugal compressors find a huge number of applications in industry and in aero-engine, the detailed analysis and comprehension of the impeller - vaned diffuser interaction is of interest in order to improve the efficiency and the operating range. This paper presents part of the results of a wide experimental campaign; data were taken at the best efficiency point in the impeller - vaned diffuser gap by a fast response probe; the single stage compressor run at 12500 Rpm and is characterised by a peripheral Mach number of 0.77. At first, data are reduced to evidence the main impeller flow features; furthermore steady diffuser effects on the impeller are commented and finally the impeller - diffuser interaction is discussed. Results evidence an effect of the diffuser on the impeller in terms of static pressure and flow velocity. Moreover, the interaction process makes the flow rate, discharged by the impeller channel, and the power exchange to be unsteady.