Numerical simulation and design methodology of a novel asymmetric cylinder profile for sliding vane vacuum pumps

Large built-in volumetric ratio is the major obstacle to improve the extraction performance of vacuum pumps. In order to achieve larger built-in volumetric ratio of the sliding vane vacuum pump (SVVP), a novel kind of asymmetric cylinder profile, called quadratic spiral, was proposed in this study. A mathematical model of the asymmetric cylinder profile and its general design methodology were presented. Moreover, the whole geometric structures of asymmetric SVVPs with single-chamber, double-chamber, and three-chamber were designed according to the proposed design methodology. Also, the comparisons between asymmetric SVVPs and symmetric SVVPs were conducted in terms of the suction and discharge volumes, and built-in volumetric ratio. The results indicated that the larger built-in volumetric ratio was realized by reducing discharge volume with the suction volume keeping constant. Numerical simulations of internal gas flows of the asymmetric SVVPs and symmetric SVVPs were carried out to compare their working characteristics. The study results showed that the asymmetric SVVPs has better working performance in terms of variational trends of pressure, smaller pressure fluctuation and energy saving.