Construction and Analysis of Hyperbolic Rotor Profile for Roots Vacuum Pump: An Analytical Study

We theoretically addressed the hyperbolic rotor profile of Roots vacuum pump to widen its application.The routine work included the construction of hyperbolic profile,derivation of parametric profile equations,specification of limiting values of key variables and calculation of the maximum shape-factor.In addition,the properties,including the dynamic imbalance,net-weight and pulsation coefficient of the hyperbolic/involute/circular-arc rotors,were evaluated and compared.The results show that the high-shaped hyperbolic rotor outperforms the involute/circular-arc rotors because of bigger volume-utilization coefficient,smaller pulsation coefficient,lighter weight,lesser internal leakage and weaker dynamic imbalance due to smaller barycenter coefficient.We suggest that the hyperbolic rotor may work well in noncontact mode because its maximum shape-factor is a little smaller than that of the involute and circular-arc rotors.