CFD-based analysis of gas flow in dry scroll vacuum pump

Based on dynamics mesh method, Computational Fluid Dynamics (CFD) simulation model of two-stage dry scroll vacuum pump was established. Simulation calculation was carried out under the condition of suction pressure at 10000Pa, 1000Pa and 100Pa,respectively. When suction pressure was 10000Pa, the numerical calculation results were basically in accordance with the experimental pumping speed. When suction pressure decreased to 1000Pa, the simulation error decreased −5.7%. When suction pressure was below 1000Pa, due to the gas regime, the calculational results deviated from the experimental results dramatically. Three-scroll profile was applied to the scroll chamberⅠ connected with the suction port, which improved the pumping speed and compression ratio as well as reducing the fluctuation of suction speed significantly. Gas expanded initially in the chamber and was then compressed by external compression. Gas compression mainly occurred in scroll chamber Ⅱ connected with the exhaust port. Gas was compressed by changing the compression chamber. The variation of the pressure in compression chamber was greatly affected by gas leakage.