Global Analysis of Tip Clearance Influence on Centrifugal Compressor Performance

In this paper a case study of a trans-sonic centrifugal compressor at various tip gap values is presented. At all clearance values, global parameters of efficiency and head coefficient were assessed for the rotor and the stage. All results were obtained through 3D CFD simulations carried out with the k-omega SST model. Results indicate that stage performance can easily be correlated with the tip gap size while rotor performances appear to be subject to more complex interactions. The work may be used to validate and extend the state of the art correlations and also to pave the way for more in-depth analysis into the phenomena occurring in centrifugal compressor flows.