Modeling and simulating of the gas flow inside a molecular pump with different geometries by Monte Carlo method to predict the compression ratio

Abstract

The molecular pump is a fixed piece in the outer space of the rotor in a gas centrifuge. The molecular pump has grooves that, when moving particles collide with it, regarding the grooves are diverted in the direction that will be routed back into the rotor. One of the molecular methods for analyzing the flow of gas inside the molecular pump’s groove is the DSMC method. In this paper, while modifying the Sickafus analytical method, a trapezoidal groove of a molecular pump and a molecular pump with full geometry have been simulated using the dsmcFoam solver in OpenFOAM. The results of DSMC simulation have been compared with the results of the modified Sickafus analytical method. Also, simulation of the molecular pump with rectangular, triangular, and semicircular geometries has been performed, and the results have been compared with the analytical method. The results show that the semicircular geometry creates the highest compression ratio during the molecular pump. Also, the results show that by improving the Sickafus analytical method, it is possible to achieve an accurate answer with a high-speed analytical method without the need to simulate the molecular pump with complex and high computing time method such as DSMC.