Design of a Centrifugal Compressor for Micro Gas Turbine: Investigation of Scaling and Tip Clearance Effects

Abstract

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

Design of a Mini Combined Heat and Power Cycle for Naval Applications

“…radial compressor and turbine, is presented. The procedure is based upon the design criteria developed and explained in detail in several papers developed by the authors for lower net power machines: in particular, the overall cycle design is presented in Barsi et al [11], while the detailed design for turbine and compressor are reported in Perrone et al [12] and Barsi et al [13], respectively. In this paper, the main results and overall performance obtained by the procedure, taking into account the scaling criteria analysed in Cumpsty [14], are presented.…”