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The dry scroll vacuum pump is a kind of variable capacity dry vacuum pump that is applied in chemical, pharmaceutical, semiconductor, and scientific instruments. Analyzing the thermodynamic characteristics of the scroll vacuum pump and studying the impact of operating temperature on its consistent performance are necessary for the design and application of the cooling system of the scroll vacuum pump. Based on the dynamics mesh method, the computational fluid dynamics (CFD) simulation model of a multi-stage dry scroll vacuum pump is established in this study. Under the suction pressure of 1000 Pa, the simulation calculation is carried out at different operating temperatures of fixed scrolls (25 °C, 45 °C, and 65 °C). The results show that the pumping speed, the gas compression power, and the energy efficiency ratio are significantly affected by different temperatures. The operating temperature of the pump has been reduced from 65 °C to 25 °C, the pumping speed is increased by approximately 5.97%, the gas compression power is increased by approximately 4.32%, and the energy efficiency ratio is increased by approximately 1.745%. This research provides a transient simulation method using dynamic mesh technology for the study of the dry scroll vacuum pump, and the results can provide a theoretical basis for the design and application of the cooling system of the dry scroll vacuum pump. [ABSTRACT FROM AUTHOR]

The scroll vacuum pump is a dry vacuum pump with a wide range of applications. The radiated noise of a multi-stage scroll vacuum pump under different suction pressures is tested. The discharge velocity field is measured by the PIV technique. When the suction pressure changes from 101 kPa to 5 Pa, the average sound pressure level of the scroll pump decreases from 80.37 dB to 58.13 dB, which is reduced by 22.24 dB. The maximum and minimum sound power levels are 97 dB and 74.76 dB, respectively. The spectrum characteristics and the distribution law of radiated noise are analyzed. The measured noises at the rear of all operating conditions are the smallest, followed by the positions above the front part, and the next is the directly above position. Aeroacoustics is the main noise source in the scroll pump. Based on the CFD method, the simulation calculation is carried out at different suction pressures and the maximum simulation error is −5.7%. The location and formation mechanism of the aeroacoustics source are analyzed. In different working processes, the main excitation sources of aeroacoustics are different. The results are helpful to the noise source identification and aeroacoustics improvement of the scroll vacuum pump. • The radiated noise of the scroll pump is experimentally investigated. • The discharge velocity field of the scroll vacuum pump is measured by PIV. • The aeroacoustics sources of the scroll pump are analyzed by CFD. • Other noises of the scroll pump are analyzed. [ABSTRACT FROM AUTHOR]

Based on CFD method and dynamics mesh method, the transient flow simulation model of dry scroll vacuum pump was established. Numerical calculation was carried out under three kinds of typical working conditions of viscous flow state including under-compression, slightly over-compression and over-compression. Simulation results are in line with the results of experiment or theoretical calculation on the whole. The maximum error of pumping speed between the simulation and the experiment is about 30%, and the minimum is close to 10%. The predicted compression power accords with the theoretical prediction of approximate polytropic process. The simulation pressure inside the pump also has a consistent change process with experimental results. The contrast and analysis of the simulation model and the physical experiments suggest that the further correctly modified geometric parameters and boundary conditions according to practical situations can significantly improve the accuracy of the numerical calculation. Further analysis of the main flow phenomena and characteristics of scroll compression chamber at the discharge side during the discharge process confirms that under-compression and over-compression lead to the large variation of gas pressure and dramatic fluctuation of compression torque. [ABSTRACT FROM AUTHOR]

Abstract: With the development of dry high vacuum pump, researches of pumping mechanism of vortex-stage are greatly concerned. This paper presents a horizontal dry high vacuum pump and establishes a numerical model of vortex stage. And then numerical simulation of flow is carried out with FLUENT software. Moreover, it studies how flow regions work on the internal flow and work performance of the vortex stage under various conditions, such as different number of blades and impeller with different blade rake. As a result, numerical simulation shows that there is a large impact on the pumping for different numbers of blades distributed on the impeller, the number of blades of single impeller should be obtained by combining with practical design sizes. In fact, this paper selects the best number of blades as forty-three by calculating and optimizing. In the mean time, there are three cases for the blade rake: pitched vanes, radial vanes and retroverted vanes. For each case, there are both longitudinal vortex and radial vortex existing in the impeller. Considering comprehensively, impeller with radial vanes is selected in the design after simulation and comparisons. [Copyright &y& Elsevier]