The aim of this paper is to investigate the design in similarity of a centrifugal\ncompressor for micro gas turbine and the related scaling effects on performance\nusing CFD investigations. This work is part of a research project carried\nout by the Department DIME of the University of Genova, with the purpose\nof investigating the performance of a micro gas turbine in the change\nfrom 100 kW electrical output to 250 kW, while maintaining the compressor\npressure ratio and geometry in similarity. The first part of the work focuses\non the comparison between the original and the scaled machine, while the\nsecond part of the study deeply investigates the tip gap effect in the new configuration.\nThe aim is to provide information about the performance of the\ncompressor designed in geometrical similarity and to evaluate the tip gap\nheight impact. From the efficiency point of view, the scaled-up machine has\nhigher efficiency (up to 1.4% increment in design conditions) keeping the\nsame technological limit for impeller manufacturing. However, the variation\nof tip gap height in the range 0 ÷ 1 mm strongly affects this parameter, leading\nto 10% alteration in design conditions between the ideal and worst case.\nThe results, both in terms of overall performance and flow fields, are widely\ndiscussed in order to obtain simple yet reliable correlation for preliminary\ndesign.
Loading....