Effect of Clearance between a Rotor and Stator of a Disk-Type Drag Pump on the Pumping Performance

고속 회전하는 원판형 드래그펌프 회전익과 고정익 사이 간극이 배기 성능에 미치는 영향

The pumping characteristics of a single-stage disk-type drag pump ( DTDP ) are calculated,for the variation of the vertical clearance between a rotor and stator and of the radial clearance between a rotor and casing wall, by the three-dimensional direct simulation Monte Carlo (DSMC)method. The gas flow mainly belongs to the molecular transition flow region. Spiral channels of a DTDP are cut on the both the upper and lower sides of a rotating disk, but the stationary disks are planar. As a consequence of results, the vertical and radial clearances have a significant effect on the pumping performance. Experiments are performed under the outlet pressure range of 0.4 $^{\sim}$ 533 Pa. When the numerical results are compared to the experimental data, the numerical results agree well qualitatively.