Presentation Information
[1F04]Numerical analysis of rarefied gas flow in a turbomolecular pump using a model Boltzmann equation
*Shun Otani1,2,3, Hiroshi Sugimoto1,2,3, Ayako Miki1,2,3, Maika Itou1,2,3 (1. Kyoto University, 2. Graduate School of Engineering, 3. Department of Aeronautics and Astronautics)
In this study, we precisely analyzed the time evolution of rarefied gas flow in a two-dimensional model of a turbomolecular pump (TMP) using a new high-speed deterministic simulation method. As a result, we proposed a more straightforward explanation for the operating principle of TMPs. Molecules entering the rotor region tend to collide with the upstream face of the rotor blades due to the rotor’s motion, while molecules entering the stator region tend to collide with the upstream face of the stator blades. These asymmetric collisions, combined with blade inclination, produce a net downward molecular flow. Based on this explanation, we demonstrated that a new design, where the rotors do not follow the wing-like shape, can operate as a pump by the same mechanism as the conventional design. Furthermore, we analyzed the effects of parameters such as blade angle, blade height, rotor speed, and gas rarefaction on the relationship between pressure ratio and flow rate.