A new method for reliable performance prediction of multi-stage industrial centrifugal compressors based on stage stacking technique: Part II-New integrated model verification

This is the second part of a conducted study to develop a new integrated model for reliable performance prediction of multi-stage industrial centrifugal compressors. The conducted evaluation in part 1 revealed a high deviation between the predicted surge flows using Casey-Robinson approach and measured values especially at low rotational speeds. Besides, a significant difference between the estimated and the experimental characteristics was observed at choke and surge conditions and this deviation is growing as the Mach number increases. One of the main disadvantages of this model is the dependency on the peak and design efficiencies and associated flow coefficients at both normal and low Mach number operations which are obviously not available at early preliminary stage. In contrast, Lüdtke method fails to detect the instable flow regions and with lower degree of accuracy in the predicted efficiencies. However, the predicted design efficiency was found very close to the experimental value. Therefore, this paper introduces a new approach to estimate the performance map of multistage industrial centrifugal compressors based on stage staking principle and by incorporating the advantages of both methods. The new model has been tested at both low and high flow coefficients applications and for vaned and vaneless diffusers. Comparing with the existing models, the developed method was proven to generate more accurate estimation for performance characteristics of multistage centrifugal compressors with less dependency on the geometrical features. One of the unique advantages of the new method is the fact that it does not require a prior knowledge of the peak and design efficiencies and associated flow coefficients.