Increasing efficiency of a two-rotor external compression machine with the three-blade rotor profile

The Roots-type two-rotor vacuum pumps are widely used to obtain the oil-free medium vacuum. The number of blades in rotors of such pumps is being increased to reduce residual pressure and the exhaust gas pulsations. The paper considers rotor profiles formed by various curves, as well as with a different number of blades. It describes a technique in constructing a three-blade profile with the elliptical rotor head. The paper invesigates a possibility in constructing a profile with different values of the casing bore radius ratio to the interaxial distance. Interrotor channel conductivity and volume utilization coefficients are computed for different ratios of the ellipse semiaxes, casing bore radius and interaxial distance for elliptical and involute two- and three-blade profiles. The resulting profile provides better pumping characteristics and, accordingly, higher efficiency compared to the two-blade and three-blade involute profiles.
EDN: KUJZWI, https://elibrary/kujzwi

References

[1] Khablanyan M.Kh., Saksaganskiy G.L., Burmistrov A.V. Vakuumnaya tekhnika. Oborudovanie, proektirovanie, tekhnologii, ekspluatatsiya. Ch. 1. Inzhenerno-fizicheskie osnovy [Vacuum technology. Equipment, design, technology, operation. Vol. 1. Engineering-physical bases]. Kazan, Izd-vo KNITU Publ., 2013. 232 p. (In Russ.).

[2] Demikhov K.E., Panfilov Yu.V., Nikulin N.K. Vakuumnaya tekhnika [Vacuum technology]. Moscow, Mashinostroenie Publ., 2009. 590 p. (In Russ.).

[3] Tran-The V., Do-Anh T. A tooth profile design for roots rotors of vacuum pump. In: ACOME-2017. Springer, 2018, pp. 1003–1016, doi: https://doi.org/10.1007/978-981-10-7149-2_70

[4] Vecchiato D., Demenego A., Argyris J. et al. Geometry of a cycloidal pump. Comput. Methods Appl. Mech. Eng., 2001, vol. 190, no. 18–19, pp. 2309–2330, doi: https://doi.org/10.1016/S0045-7825(00)00236-X

[5] Hsieh C.-F., Hwang Y.-W. Study on the high-sealing of roots rotor with variable trochoid ratio. J. Mech. Des., 2007, vol. 129, no. 12, pp. 1278–1284, doi: https://doi.org/10.1115/1.2779897

[6] Wang S., Li H., Zhao Y. at al. The improvement study of involutes profile type rotor profile in Roots vacuum pump. Int. Conf. on New Technology of Agricultural, 2011, pp. 251–253, doi: https://doi.org/10.1109/ICAE.2011.5943796

[7] Li Z., Wang X. New cycloid rotor profiles design under different rolling circle radii for Roots vacuum pumps. SN Appl. Sci., 2022, vol. 4, no. 10, art. 280, doi: https://doi.org/10.1007/s42452-022-05174-x

[8] Li Z., Yang S., Wang X. at al. Analysis and construction of a parabolic rotor profile for Roots vacuum pumps. J. Phys.: Conf. Ser., 2021, vol. 1952, art. 042108, doi: https://doi.org/10.1088/1742-6596/1952/4/042108

[9] Tran N.-T., Nguyen D.-M. Analysis of flow characteristics of cylindrical and helical type multi-lobe roots blower. Eureka: PE, 2023, no. 1, pp. 67–75, doi: https://doi.org/10.21303/2461-4262.2023.002578

[10] Zhou S., Jia X., Yan H. at al. A novel profile with high efficiency for hydrogen-circulating Roots pumps used in FCVs. Int. J. Hydrog. Energy, 2021, vol. 46, no. 42, pp. 22122–22133, doi: https://doi.org/10.1016/j.ijhydene.2021.04.038

[11] Wang J., Liu R., Yang S. at al. Geometric study and simulation of an elliptical rotor profile for Roots vacuum pumps. Vacuum, 2018, vol. 153, pp. 168–175, doi: https://doi.org/10.1016/j.vacuum.2018.04.014

[12] Wu Y.-R., Tran V.-T. Generation method for a novel Roots rotor profile to improve performance of dry multi-stage vacuum pumps. Mech. Mach. Theory, 2018, vol. 128, pp. 475–491, doi: https://doi.org/10.1016/j.mechmachtheory.2018.06.009

[13] Burmistrov A.V., Karablinov D.G., Bronshteyn M.D. Effect of geometrical parameters of elliptical profile on characteristics of twin-rotor vacuum pumps of Roots type. Kompressornaya tekhnika i pnevmatika, 2004, no. 6, pp. 38–40. (In Russ.).

[14] Burmistrov A.V., Salikeev S.I., Bronshteyn M.D. Pryamye i obratnye potoki v beskontaktnykh vakuumnykh nasosakh [Direct and reverse flows in non-contact vacuum pumps]. Kazan, Izd-vo KGTU Publ., 2009. 231 p. (In Russ.).

[15] Burmistrov A.V. Sozdanie i issledovanie beskontaktnykh vakuumnykh nasosov. Diss. dok. tekh. nauk [Design and study on non-contact vacuum pumps. Doc. tech. sci. diss.]. Kazan, KGTU Publ., 2006. 451 p. (In Russ.).

[16] Salikeev S., Burmistrov A., Bronshtein M. et al. Non-contact vacuum pumps. A general purpose method for conductance calculation of profile slot channels. Vak. Forschung und Prax., 2014, vol. 26, no. 1, pp. 40–44, doi: https://doi.org/10.1002/vipr.201400542

[17] Hirano T., Yamada K., Fujii T. Roots type fluid machine. Patent US 7320579. Appl. 08.12.2006, publ. 22.01.2008.