Bulletin of JSME
Online ISSN : 1881-1426
Print ISSN : 0021-3764
The Axial Flow Molecular Pump : 4th Reprot, Performance of a Rotor with a Single Blade Row in the Transition Flow Regime
Tadashi SAWADA
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ジャーナル フリー

1973 年 16 巻 96 号 p. 993-1001

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抄録
As a forevacuum pump of an axial flow molecular pump, a diffusion pump is commonly used. In this case, the pressure in the forevacuum side of the molecular pump is kept below 10-4 mmHg, and therefore a free molecule flow takes place in all the blade rows. Occasionally, only a rotary pump is used as the forevacuum pump. In this case, the pressure in the forevacuum side is 10-3∼10-2 mmHg and collisions between gas molecules occur as frequently as between gas molecules and blade plates of some rows placed near the forevacuum side. This state is called the transition flow regime. The performance of a rotating blade row in this regime is studied theoretically and experimentally. The theoretical performance agrees with the experimental results when the Knudsen number is larger than 5 to 1, but the difference between the theoretical and experimental results increases as the Knudsen number decreases.
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© The Japan Society of Mechanical Engineers
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