Aerodynamic Tests on Centrifugal Process Compressors—Influence of Diffusor Diameter Ratio, Axial Stage Pitch, and Impeller Cutback

Almost all process compressors manufactured today are built in accordance with the fixed geometry modular system. It is not always possible to accurately predict the operational behavior of a compressor, particularly in such cases where a deviation from the standard solution is advisable or even necessary. This paper describes and analyses by means of experimental measurements the influence of three different stage modifications (axial stage pitch, shortening of the vaneless annular diffusor, blading cut-back). The results given here are directly related to engineering practice as they enable the design engineer to apply realistic efficiences even for modified stages in the early planning stage.