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Summary The influence of the number of lobes on the working process of Roots vacuum pump is examined using the production vacuum pump NVD‐200 with a rotor profile based on an elliptical curve as a prototype. Design with two‐lobe, three‐lobe and four‐lobe rotor profiles was considered. Calculation of the main parameters characterizing profile quality (area‐utilizing ratio and conductance of rotor mechanism clearances) was carried out. The influence of rotor “plumpness” on pumping characteristics was studied. It is shown that the number of lobes providing the maximal pumping speed is different depending on the geometric parameters of the rotor.
Raykov et al. (Sat,) studied this question.