Study On Profile Of The Spiral Rotor And Pumping Mechanism Of High Vacuum Dry Pump

In recent years, with the rapid development of vacuum technology and related areas improving, people have started to develop a variety of vertical air dry vacuum pump, which can replace the work of high-vacuum units. Recently, there have been vertical air dry high vacuum pumps in abroad, only the pump can achieve the pumping process of high vacuum from the atmosphere. And the pumps have achieved the commercial, applied in practical production. But this dry pumps are still blank in domestic now.This article describes the structure and working principle of high vacuum dry pumps, and compares several vacuum-type lines. The final screw rotors choose a more specific profile. Meanwhile, the internal flow characteristics of spiral rotors were simulated with the Monte Carlo study.Currently, direct simulation Monte Carlo (DSMC) method is effective in the rarefied gas simulation. Especially between the molecular flow and over-flow state, only this method can simulate three-dimensional state of molecular motion. It uses the division of cells using the method, movement and collision decoupling method, sampling collision method and random number method in molecular motion; and sets the initial parameters of the simulation to describe the molecular states; statistics and analysis molecular movement, collision, reflection and rotation; records the location of elements, speed, temperature, molecular number density, degree of freedom, momentum, kinetic energy and other micro-parameters. This article can come to the macroscopic gas flow parameters, flow characteristics.In this paper, pumping process of high-vacuum dry pumps helical rotor is used the direct simulation Monte Carlo method to research, under Ba Dechun and Liu Kun teachers guidancing, I studies the molecular temperature, surface temperature, collision model and so on. Finaly, I obtained Helical rotors geometric parameters on the pump exhaust efficiency; also got the surface temperature of channel and the gas pump exhaust temperature on the properties of molecular influence law. Harden sphere model (VHS model) and the variable soft-sphere model (VSS model) in the pumping performance simulation results are very close, and the two methods can be used in high vacuum dry pumps helical rotor performance level; final, pumping speed of high vacuum dry pumps was verified from theory.