a new modeling method to reveal pumping mechanism of turbomolecular pump

In order to meet the calculating requirements of high speed and miniaturized turbomolecular pump (tmp), anew modeling method is proposed for a rotor-stator row. in the same cartesian coordinate system, theanalytical equations of blade row are derived according to the real three-dimensional geometric model. aself-defining procedure is written to simulate the flow of gas molecules in tmp based on test particle montecarlo method. the procedure not only can calculate transmission probability of rotor row, stator row and arotor-stator row but also evaluate the pumping performance of different blade parameters. the simulationresults and known experimental data have a good agreement to confirm the feasibility of presented modelingmethod. the flow analysis shows that molecules at outlet of rotor row tend to accumulate in large radius andthis phenomenon is obvious for high rotational speed. the differences were found between a single-stage rowand a rotor-stator row. in rotor row, the molecular density at the rear blades is the highest. this is beneficialfor pumping speed of tmp because 57% of molecules at the rear blades are likely to reach outlet. this willprovide a direction for the structural optimization design of the blades in the future. in stator row, themolecular density reaching outlet does not significantly increase with the increase of blade velocity ratio,which indicates that the stator row is mainly used to increase the pressure ratio of tmp. the analysis ofmolecular density in each region reveals the pumping mechanism of tmp.