| Summary: | 碩士 === 國立中正大學 === 機械工程系研究所 === 106 === Foil gas bearing have wide industrial applications, mainly in micro-turbine engine and the aircraft industry else. Micro-turbine is the small size of gas turbine, and only equipped with single layer compressor and a turbine, which make the machine system having the advantage of small volume and suitable for high- speed rotating application. Turbine engine also have the need for long-time running lubrication system. Most important, air foil have remarkable potential for both aspect.
This research project applies a lubrication system to meet the technology vision; developing a 80kg-thrust micro-turbine engine in the use of micro-turbine generator, small high-speed target drone, life propulsion system of standard high speed trap and long high speed rotating operations. In the application of high speed micro-turbine engine, the micro-turbine power system has the long running time requirements with the rotating speed up to 90,000 to 100,000 rpm and life needs ( for 30kW ) over 30,000 hours, so the primary is to choose a proper bearing lubrication system in the need of high speed and long time rotating. From the previous research, knowing spindle rotates in high speed and usually works in the environment of high temperature. Applying rolling or fluid hydrodynamic bearing, we need to use an efficient cooling system to make sure bearing working performance. Foil gas bearing isn’t vulnerable to temperature change, so we don’t need the cooling system in the allowable temperature range of foil material. Therefore we choose foil gas bearing, having high speed rotation and long-time operation, as the lubrication system and hope to enhance power efficiency and life-cycle of micro-turbine generator .
We need lots of experience for the bearing design because it’s complicated to manufacture. For the purpose of making shaft lift, we set up a simulation and analysis system. Therefore, it’s needed to use related patent and article as reference and then take the calculation of experiment trend and result of simulation into account to analysis. After, provide the analysis result with reference data for research organization. While the design of the foil is the key aspect of affecting the performance of foil gas bearings, this research start with surface roughness of top foil and use the full-film hydrodynamic lubrication theory to calculate the minimum film thickness used for supporting shaft lifting. Try to reach the stiffness in the theory calculation with the calculation of programming language and design geometry foil for stiffness. Studying research analysis on present bump foil is also necessary. Eventually, hope to enhance the load capacity and reliability of foil gas bearing in real working.
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