Design and operational behaviour of the rear stages of an industrial axial compressor

Due to mass flow adaptations of the downstream process Industrial Axial-flow compressors need wide operating ranges. To meet these requirements a new blading for the rear stages was designed which enabled a large extension of the performance curves between surge and choke line. Measured performance of a 6 stage research compressor having repeating blading showed aspired high efficiencies together with a wide operating range. These improvements are attributed to the optimised design with CD-profiles together with the choice of a high degree of reaction for this application. Calculated performance maps with different guide vane positions show a good agreement of the measured surge-lines with the theoretical performance range of the different profile sections.