The effect of startup modes on a vacuum cam pump

Abstract

In this paper the dynamic mesh model and local mesh reconstruction was used to explore the transient behavior of the vacuum cam pump during startup periods. The numerical study was performed on the pump with five different startup modes. The results reveal the regularity of flow fluctuation, pressure pulsation and force variation of the rotor during the startup process of the vacuum cam pump in different startup modes. As for the results, it is found that the internal flow characteristics of vacuum cam pump shows obvious transient behavior during startup. Reflux phenomenon appears at the outlet of the pump and tends to stabilize after the start time is completed in the linear startup modes. But the out-flow rate of exponential mode tends to stabilize at about 0.05s, which is obviously ahead of startup time. Moreover, due to the internal instantaneous flow manifests itself as a violent collision, the maximum Fy reaches to 430 kN and Fx reaches to 70 kN respectively when the pump startup normally. However, using exponential and linear startup modes can significantly reduce the transient force load impact of the rotor in the starting moment. Meanwhile, the static pressure pulsation of the inlet and outlet weakens obviously until the rated speed is reached, then the pressure pulsation tends to be stable.