The advancement in the design and prototype testing of an ultra-micro gas turbine set for portable electrical generation is reported in this paper. The extremely small power requirements (300 W) pose severe restrictions both to the Designer's and to the Technologist's choices: the present specifications lead to rotor diameters of about 10 (compressor) and 13 mm (turbine) and as a consequence to extremely high rotational speeds (4-500000 rpm). Previous studies have shown that the attainable cycle efficiency is rather low (below 10%): therefore, a regenerative cycle has been adopted here. The turbine entry temperature is much lower than current industrial standards for large-scale machines, because the selected material (SiC) cannot exceed 1000°C and more advanced ceramic materials have raised concerns about their fragile behaviour especially during on-off transient operation. A back-to-back radial/radial configuration is presented here: the blade geometry is specifically studied to attain the maximum possible fluid dynamic efficiency and to be easily manufactured (no blade twisting: the profiles are simply extruded from the hub to the tip, and their shape has been "optimized" in a previously published series of CFD simulations). A thermo-mechanical stress analysis of the rotating assembly has been performed, and some critical issues resolved, so that neither rotor is near failure under realistically "hot" operating conditions. A mockup has been built to undergo cold flow tests (not reported here).
Progress in the development of a prototype “Ultra-Micro” Gas Turbine Set for Portable Power Generation / Capata, Roberto; Sciubba, E.. - (2008), pp. 573-580. (Intervento presentato al convegno ECOS 2008, tenutosi a Cracow-Gliwice; Poland nel Giugno 24 – 27, 2008.).
Progress in the development of a prototype “Ultra-Micro” Gas Turbine Set for Portable Power Generation
CAPATA, Roberto;
2008
Abstract
The advancement in the design and prototype testing of an ultra-micro gas turbine set for portable electrical generation is reported in this paper. The extremely small power requirements (300 W) pose severe restrictions both to the Designer's and to the Technologist's choices: the present specifications lead to rotor diameters of about 10 (compressor) and 13 mm (turbine) and as a consequence to extremely high rotational speeds (4-500000 rpm). Previous studies have shown that the attainable cycle efficiency is rather low (below 10%): therefore, a regenerative cycle has been adopted here. The turbine entry temperature is much lower than current industrial standards for large-scale machines, because the selected material (SiC) cannot exceed 1000°C and more advanced ceramic materials have raised concerns about their fragile behaviour especially during on-off transient operation. A back-to-back radial/radial configuration is presented here: the blade geometry is specifically studied to attain the maximum possible fluid dynamic efficiency and to be easily manufactured (no blade twisting: the profiles are simply extruded from the hub to the tip, and their shape has been "optimized" in a previously published series of CFD simulations). A thermo-mechanical stress analysis of the rotating assembly has been performed, and some critical issues resolved, so that neither rotor is near failure under realistically "hot" operating conditions. A mockup has been built to undergo cold flow tests (not reported here).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
