| Budget Amount *help |
¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
Recently, small sized power generators with high output density have been strongly required as the sizes of industrial products are getting smaller. In the middle of 1990's, MIT have proposed ultra-micro gas turbines which could rotate at 1 million rpm as a portable power generator and, since then, many researches have actively studied various issues on this area. Portable power generators using an ultra micro gas turbine have the advantage that they can produce one order higher power density compared with lithium battery and, hence, are considered to be a next generation of portable power source. In these ultra-micro gas turbines, aerodynamic bearings are usually used due to low friction, excellent stability at high speeds and the capability for high temperature environment. Accordingly, aerodynamic bearings with higher stability are necessary for these devices to improve gas turbine performances.
In order to solve the above problem, we proposed the improved method of stability of aero
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dynamic bearings and planed to develop an aerodynamic bearing which could rotate at speeds over 1 million rpm.
Based on the calculated results conducted in 2004, a herringbone grooved aerodynamic bearing with a floating bush was designed and manufactured. In order to flexibly support the floating bush, two different methods were tested. One is a floating bush using pressurized air generated by herringbone grooves. The other is a floating bush supported by thin flexible foils. The experiment was conducted to confirm the stability of these proposed bearings. As a result, we obtained the following conclusions.
(1).The proposed aerodynamic bearings with a floating bush could stably support the shaft at speeds over 0.5 million rpm.
(2).The pressurized air generated by the viscous effect of herringbone grooves could support the weight of a floating bush and, hence, the shaft could stably rotate even when it was horizontally set due to the effect of a floating bush.
In these experiments, we could not rotate the shaft over 0.5 million rpm because the power limitation of air turbine. In the near future, we plan to rotate the shaft over 0.5 million rpm by using the supersonic nozzles. Less
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