Calculation of the Actual Radial Clearance when Simulating the Working Process of an Oil-Free Volute Vacuum Pump

The volute vacuum pumps provide an oil-free medium vacuum due to low backflows and the guaranteed clearance between the spirals. When developing volute pumps, the minimum radial clearance ensuring contactless movement of the spirals is determined for any normal operating conditions. The article considers a method for calculating the radial clearance of an oil-free volute pump. The gas forces acting on the working elements of the vacuum pump do not change significantly the radial clearance. Since the spirals are made of aluminum alloys, the main effect on the radial clearance change is caused by thermal deformations of the spiral elements. This change can reach up to 25%, and during pump operation the clearance decreases for external cavities and it increases for internal ones. To find the most accurate value of the radial clearance, it is necessary to use the results of measurements of the spiral element profile parts as an initial approximation. Comparison of calculated and experimental indicator diagrams confirmed the adequacy of the proposed methodology.

References

[1] Raykov A.A., Salikeev S.I., Burmistrov A.V. Spiral’nye vakuumnye nasosy [Spiral vacuum pumps]. Kazan’, Izd-vo KNITU Publ., 2018. 220 p. (In Russ.).

[2] Khablanyan M.Kh., Saksaganskiy G.L., Burmistrov A.V. Vakuumnaya tekhnika. Oborudovanie, proektirovanie, tekhnologii, ekspluatatsiya. Ch. 2. Vakuumnye nasosy [Vacuum technics. Equipment, design, technologies, exploitation. P. 2. Vacuum pumps]. Kazan’, Izd-vo KNITU Publ., 2016. 300 p. (In Russ.).

[3] Paranin Yu.A. Sovershenstvovanie metoda rascheta rabochego protsessa spiral’nogo kompressora sukhogo szhatiya s ispol’zovaniem rezul’tatov eksperimental’nykh issledovaniy. Diss. kand. tekh. nauk [Improving method for calculation of working process in a dry spiral compressor using results of experimental studies. Kand. tech. sci. diss.]. Kazan’, KGTU Publ., 2011. 254 p. (In Russ.).

[4] Raykov A.A., Yakupov R.R., Salikeev S.I. et al. Thermal deformation simulation of scroll elements in oil-free scroll vacuum pump. Vestn. Mosk. Gos. Tekh. Univ. im. N.E. Baumana, Mashinostr. [Herald of the Bauman Moscow State Tech. Univ., Mechan. Eng.], 2015, no. 3, pp. 92–102, doi: http://dx.doi.org/10.18698/0236-3941-2015-3-92-102 (in Russ.).

[5] Spille-Kohoff A., Hesse J., Andres R. et al. CFD simulation of a dry scroll vacuum pump with clearances, solid heating and thermal deformation. IOP Conf. Ser.: Mater. Sci. Eng., 2017, vol. 232, art. 012052, doi: https://doi.org/10.1088/1757-899X/232/1/012052

[6] Yue X.J., Zhang Y.L., Su Z.H. et al. CFD-based analysis of gas flow in dry scroll vacuum pump. Vacuum, 2017, vol. 139, pp. 127–135, doi: https://doi.org/10.1016/j.vacuum.2017.02.019

[7] Raykov A.A., Yakupov R.R., Burmistrov A.V. et al. Deformation of working elements of dry scroll vacuum pumps. Izvestiya vysshikh uchebnykh zavedeniy. Mashinostroenie [BMSTU Journal of Mechanical Engineering], 2015, no. 1, pp. 57–63, doi: http://dx.doi.org/10.18698/0536-1044-2015-1-57-63 (in Russ.).

[8] Ibragimov E.R. Povyshenie effektivnosti spiral’nogo kompressora sukhogo szhatiya. Diss. kand. tekh. nauk [Raising efficiency of a dry spiral compressor. Kand. tech. sci. diss.]. Kazan’, KGTU Publ., 2009. 134 p. (In Russ.).

[9] Burmistrov A., Salikeev S., Raykov A. et al. Mathematical model of working process of oil free scroll vacuum pump. Influence of leakage and heat transfer on pumping characteristics. Vak. Forschung und Prax., 2017, vol. 29, no. 6, pp. 28–31, doi: https://doi.org/10.1002/vipr.201700663

[10] Sun S., Wang Z., Guo P., et al. Optimization of the tip profile of orbiting scroll in an asymmetry suction chamber scroll compressor. IOP Conf. Ser.: Mater. Sci. Eng., 2021, vol. 1180, art. 012014, doi:10.1088/1757-899X/1180/1/012014

[11] Burmistrov A., Salikeev S., Bronshtein M. et al. Conductance calculation of slot channels with variable cross section. Vak. Forschung und Prax., 2015, vol. 27, no. 1, pp. 36–40, doi: https://doi.org/10.1002/vipr.201500571

[12] Ansys Inc. license file for Kazan National Research Technology University no. 657938.

[13] Tyurin A.V., Raykov A.A., Salikeev S.I. et al. Experimental indicator diagrams of scroll vacuum pump. Kompressornaya tekhnika i pnevmatika [Compressors and Pneumatics], 2018, no. 4, pp. 12–15. (In Russ.).

[14] Tyurin A.., Burmistrov A., Salikeev S. et al. Indicator diagrams of oil free scroll vacuum pumps. Vak. Forschung und Prax., 2019, vol. 31, no. 4, pp. 34–37, doi: https://doi.org/10.1002/vipr.201900717

[15] Portal’naya koordinatno-izmeritel’naya mashina Zeiss Contura [Zeiss Contura portal coordinate-measuring machine]. zeiss-solutions.ru: website. URL: https://zeiss-solutions.ru/equipment/promyshlennaya-metrologiya/koordinatno-izmeritelnye-mashiny/zeiss-contura (accessed: 05.12.2021). (In Russ.).