[2P01-53] Poster Presentation

[2P31] Experimental study of conductance in narrow rectangular channels from molecular to viscous flow

*Tetsuro Ikeyama¹, Tsutomu Nishihashi², Hantarou Ozawa², Toshiaki Kisaki¹, Akihito Okamoto¹, Tomonari Tanaka² (1. Graduate School of Engineering, Osaka University, 2. ULVAC, Inc.)

A dry screw pump operates with clearances between the rotor and its follower, as well as the housing during its operation. The aim of this study is to derive the conductance of the clearances within the dry vacuum pumps. We assumed the clearance between the rotor and the housing as narrow rectangular channels. However, there are few reports that have measured the conductance of such channels through flow rate experiments. Therefore, we conducted flow rate measurements through such channels and calculated their conductance. We compared the conductance of rectangular channels proposed by Sasaki et al., Kieser et al. and O'Hanlon with experimental results. O'Hanlon’s model agreed relatively with the experimental data in Kn > 0.01 (Knudsen number based on the short side of the channel) region and deviated in Kn < 0.01 region. Therefore, we investigated theoretical approximations to better fit our experimental data in the low-pressure regime and dependence on channel dimensions.