Fuel supply systems used in microgasturbines are designed in experimental way. In literature they exist as geometrically prescribed that is proper in general. In commercial aeroengines injection system is the most vulnerable part which failure generates high thermal loads and causes overheating of whole "hot section " or part of it. Microgasturbines are subjected to overheating due to relative short combustion section and uneven fuel distribution in injection points. Presented article contains preliminary research of fuel injector ring designed for microgasturbine turbojet. Tested fuel collector is supplied from the single source and feeds five vaporizers. Investigations are focused on mass flow measurement from each supply point. Research methodology is similar to supervisory tests carried out on commercial aeroengines. Injector was tested with two types of microfuelpumps: JetCAT A60I405 and FlightWorks 200C. As a working liquid the JET A l kerosene was used For each probe constant volume of liquid was pumped through the system. Pumps were tested infull operational range of voltage. Electric power characteristics were obtained for fuel pump and whole fuel system. The strong influence of throttling on stability of microfuelpumps was affirmed. As a conclusion there is a modernization proposal that aims on quality and quantity of fuel distribution.
During the development of the small gas turbine, the most important calculations comes from preliminary design process which gives a shape of airflow duct and limits available space for each component of the engine. Micro scale jet engines are not simply reduced-scale model of the full-size engines. The basic method of working is the same, but the are special considerations which demands a different approach to the main design. There are few similarities to the first generation of turbojets, for both critical dimensions comes from compressor and combustor. Micro gas turbine in the contrast to jet engines does not possess the mechanical coupling to the group of accessories. All accessories are electric driven. Small fuel pumps supply fuel line with pressure that hardly exceeds pressure that comes from compressor. The lubrication system is connected to the main fuel line. Bearings are lubricated with mixture of kerosene and turbine oil. Main difficulties in the process of preliminary design come from connecting of the each engine component. Narrow margin that consist limitations from rotational speed, overall dimensions, thermal and centrifugal loads ,overall efficiency and lack of knowledge about design process for small gasturbine makes up challenge for skilled designers.
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