The present study has been carried out to develop a computational procedure for the preliminary design and the off-design performance analysis of centrifugal compressors with vaneless diffusers by integrating empirical loss models and analytical equations.
Losses in centrifugal compressors stem from a number of sources and their exact calculation is not yet possible. This study investigates several modeling schemes and shows that a fair-to-good prediction can be achieved by a proper selection of the most important flow parameters resulting from a meanline one-dimensional analysis.
The performance maps for compressors are calculated and compared with measured-performance maps. Choking flow is generally well predicted, and the off-design performance characteristics in terms of the pressure ratio vs. mass flow produced have generally correct form. However, no universal means have been found of predicting accurately the onset of surge.
The prediction method developed through this study can serve as a tool to ensure good matching between parts and it can assist the understanding of the operational characteristics of general purpose centrifugal compressors.
