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Казанский национальный исследовательский технологический университет, г. Казань, Российская Федерация Аннотация Ключевые слова Безмасляные спиральные вакуумные насосы широко распространены в нанотехнологиях, микроэлектронике, медицине, фармацевтике и термоядерной энергетике. Разработка новых типоразмеров насосов и улучшение существующих удельных характеристик возможна лишь на основе надежной математической модели рабочего процесса, позволяющей оценить влияние тех или иных факторов на процесс откачки. Выполнено математическое моделирование рабочего процесса безмасляного спирального вакуумного насоса с быстротой действия 12 м 3 /ч. Приведены результаты расчетов быстроты действия при различных частотах вращения приводного вала (согласование с экспериментом составляет ~ 20 %). Разработанную модель рабочего процесса безмасляного спирального вакуумного насоса можно рекомендовать для расчета откачных характеристик безмасляных спиральных вакуумных насосов Спиральный вакуумный насос, метод конечных объемов, быстрота действия, проводимость, обратные перетекания, процесс откачки

Experimental study of pumping characteristics of a pilot model of a claw single‐stage vacuum pump with identical rotors was carried out. The curves of pumping speed vs. pressure at different rotary speed and the ultimate pressure at different rotors speed were determined on a test unit. Indicator pressure diagrams in working chambers of claw vacuum pump were obtained with the help of special sensors. Thus, an experimental data bank concerning the pumping characteristics of claw vacuum pump was created. It may be used for estimation of mathematical model adequacy and further development of the pump design.

Summary In this paper influence of rotor profile type of Roots vacuum pumps on backward leakage through channels of rotor mechanism and pumping speed is considered. Elliptical, involute, and circular profiles are widely used. Backward leakage through channels of rotor mechanism with different rotor profiles is determined from conductance which was calculated by angular coefficients method for free molecular flow regime at different rotors rotating angles. It is shown that backward leakage is maximal at rotors rotating angles 25–45° due to maximal inter‐rotor channel opening for gas flow and is minimal at 0°. Elliptical rotor profile provides minimal backward leakage over one revolution. Numerical modeling of Roots pump working process was carried out on the basis of CFD ANSYS‐CFX complex by dynamic meshing method. SST turbulence model was used for calculations. It is confirmed that maximal pumping speed is provided by Roots pump with elliptical rotor profile.

Mathematical model of oil free claw vacuum pump is presented. The model is based on energy balance differential equations of thermodynamic system of variable mass working body. Using the equations of coordinates transformation and contact line of rotors continuity condition, equations for geometry of сlaw pump working chamber on condition of rotors point connection are obtained. To evaluate the leakage through the rotor mechanism channels, their existence graphs are plotted and geometric parameters of the channels depending on rotors position are determined.As a result of modeling, dependence of pressure and temperature in suction and compression-discharge chambers on rotation angle at different rotary speeds and on different inlet pressures and relationship between pumping speed and inlet pressure are obtained.The comparison between calculated values and experimental data obtained for one-stage claw pump with identical rotors is carried out. The maximal difference between the calculated and experimental values does not exceed 15 %. The developed mathematical model is recommended for analysis of influence of rotors geometry on the working process parameters and pumping characteristics of an oil free claw pump. SUMMARY L A ∆ α δ RR δ S1 δ S2 δ RS R S FIGURE 1: Main dimensions of a claw vacuum pump.