Analysis of Unstable Radial Compressor Operation in a System With Large Plenum Volume: Mathematical Modelling and Experimental Results

The paper focusses on the numerical and experimental investigation of the operation of a centrifugal compressor connected to a large plenum volume. The experimental study consisted of measurements of time-averaged and transient pressure values in a system based on the DP1.12 blower. The numerical analysis was based on the Greitzer model. The model parameters were determined so as to achieve best fit with the experimental signal. It was observed that out of two optimal solutions, one resolved the first harmonic of oscillations significantly better than the other. The obtained values of the B parameter varied with the operation point, which is contrary to the formal definition of this quantity. The values of angular Helmholtz frequency ω_h were not sensitive to the change of operation point. This paper improves our understanding of the meaning of model parameters, which is a crucial step towards a more accurate prediction and prevention of surge.