The modifications of meridional form and blade thickness of the impeller of an industrial radial compressor stage (impeller outlet blade angle 32 deg., relative width parameter 0.05) have been designed to extend the operating range of the stage in the area of higher flow rates and to reduce aerodynamic losses in this region. Quasi-3D calculations of the flow pattern in both original and modified impeller flow channels have been carried out to assess the influence of channel form change. The aerodynamic performance of the stage operating with both impellers has been tested on a test rig. The original stage was equipped with varied diffuser only, the modified one was tested with both vaned and vaneless diffusers. Detailed measurements of the flow field behind the impeller outlet have also been carried out. The results of these investigations are presented. Aerodynamic performance and losses in individual flow parts of the stages are compared and discussed.

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