Investigation of the Solidity and the Blade Vibration Behaviour of Unshrouded Centrifugal Compressor Impellers With Different Aerodynamic Design

Abstract

The efficiency and the characteristics of unshrouded centrifugal compressors depend on the thermodynamic and aerodynamic design of the stage and especially of the impeller. Both, the efficiency and the characteristics, can strongly be influenced by a variation of the geometry of the blade structure. The design of the leading edge depends on the given inlet flow angle distribution and the outlet part of the blade is fixed by the desired outlet angle distribution. Due to the manufacturing process, the selected material, the solidity and the blade vibration, the restrictions and limitations have to be taken into consideration during the aerodynamic optimization process of the blade geometry. By means of Finite Element Code computations of the solidity and the vibration behaviour the possibilities, the restrictions and the limits of a modern aerodynamic design especially in the inlet and outlet part of the impeller blades were investigated. The results of this work could demonstrate the importance of integrating the Finite Element Code computation in the design process — not only to see the limits, but also to try and realize new ideas of design optimization.