An Enhanced Greitzer Compressor Model Including Pipeline Dynamics and Surge

Abstract

The modeling of a centrifugal compressor system with exhaust and plenum piping acoustics is presented in this paper. For an experimental centrifugal compressor test rig with modular inlet and exhaust piping, a mathematical model of the system dynamics is derived based on the Greitzer compression system model. In order to include the dynamics of the piping acoustics, a transmission line model is added to the original compressor equations and different compressor-piping configurations were tested. The resulting mathematical representations of the compression system dynamics are compared with the measured response of the experimental setup. Employing active magnetic bearings to perturb the axial impeller tip clearance of the compressor, the compression system is excited over a wide frequency range and the input-output response from the impeller tip clearance to the plenum pressure rise is analyzed. Additionally, the simulated surge oscillations are compared with the measured response in the surge condition. A good agreement is observed between the experimental and theoretical frequency responses of from the tip clearance to the output pressure, both in stable operation and during surge.