| Budget Amount *help |
¥8,700,000 (Direct Cost: ¥8,700,000)
Fiscal Year 1998: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1997: ¥7,000,000 (Direct Cost: ¥7,000,000)
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| Research Abstract |
Gas film bearings are used for supporting high-speed rotating machinery such as gas expander, turbo-pomp, high-speed motor and so on. Especially, stepped gas bearings are widely used for such machinery because of their simple structure, high load carrying capacity and high stability. However, conventional type of stepped gas film bearing has disadvantage of low damping capacity for sudden changes of applied load, for example, impulsive load.
The aim of this research is to develop a new type of hydrodynamic stepped thrust gas film bearings by use of the piezo-type actuators to control actively the step height. The experimental apparatus was designed, in which the range of rotational speed is from 10000rpm to 40000rpm and the shaft is rotated with built-in-type high speed motor. The number of pads is six, the pad extent angle is 58deg., the outer diameter of pad is 32mm, the applied loads are 1.5kg to 2.0kg, respectively. These variables were determined by the hydrodynamic lubrication theory including the inertia effects at the step. Using such type of apparatus, the spring and damping capacity of gas film can be controlled actively with varying the step height.
On the other hand, the static and dynamic characteristics of stepped thrust gas bearings are theoretically examined for a wide range of operating conditions. From the numerical results, the combined effects of fluid. film inertia at the step and compressibility of gas film on the bearing characteristics were clarified.
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