High Hub/Tip Ratio Centrifugal Compressors

During WW II the impetus of higher speed higher altitude aircraft necessitated the rapid development of advanced supercharged and turbocharged piston engines, much of the centrifugal compressor technology from which was transferred to early gas turbines. Post WW II gas turbine development was predominantly focused upon the perfection of the multistage axial compressors, with the recognition that in certain applications the combined axial–cum–centrifugal compressor (AxC) could provide a more compact engine installation. Gas Turbines with AxC compressors now fulfill a significant sector of the aviation propulsion market, plus also some industrial applications. Individual research and development of both axial and centrifugal compressors types continues to higher plateaus of performance, and is the context of extensive publications, yet in difference a scarcity of written technology prevails for the AxC compressor. This conspicuous limited exposure of AxC compressor technology fostered the motivation for this treatise, the intent being to record whatever meager AxC information at large exists, plus highlighting turbomachinery design parameters which can assist in AxC continued performance perfection. Specifically a characteristic design feature of AxC examined is the influence of large impeller hub to tip diameter ratios Є.