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Modelling of inhomogeneous chamber states in rotary positive displacement vacuum pumps.

Number: A2-162

Author(s) : PLESKUN H., JUNEMANN T., BODE T., BRÜMMER A.

Summary

Chamber model simulation is a common approach to simulate rotary positive displacement vacuum pumps. Therefore the pump is abstracted into working chambers and connecting clearances, whereby the clearance leakages can be identified as the major loss mechanism in such machines. The clearance mass flow rates are calculated with respect to the thermodynamic states in the adjacent chambers, which are normally considered to be homogeneous. In this work it is shown, that the chamber state is inhomogeneous for rarefied gases due to the movement of the pistons which causes a pressure gradient within the chamber. This effect increases with higher Knudsen numbers, because of the increasingly dominant friction. An efficient way to model these inhomogeneous states with a one-dimensional approach for geometrically abstracted chambers is shown. The approach is applied to chamber model simulations of a screw spindle vacuum pump (SSVP) and the results are compared to simulations with homogeneous chamber states and to measurements.

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Pages: 10

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  • Original title: Modelling of inhomogeneous chamber states in rotary positive displacement vacuum pumps.
  • Record ID : 30028734
  • Languages: English
  • Subject: Technology
  • Source: 12th International Conference on Compressors and their Systems
  • Publication date: 2021/09
  • Document available for consultation in the library of the IIR headquarters only.

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