Numerical investigation of the blade angle in the middle and final stages of a five-stage turbomolecular pump by considering the effect of returning molecules from other stages using the TPMC method

Document Type : Original Article

Authors
mojtaba sadeghian
Miralam Mahdi
Mech. Eng., Shaid Rajaee Teacher Traning Univ., Tehran, Iran
10.22034/stme.2023.409015.1041
Abstract
In this research, after examining the theoretical and experimental work done in the field of turbomolecular pumps, the simulation of the behavior of molecules in the free molecular flow between the stages of the turbomolecular pump, considering the effect of returning molecules from other stages, will be done. This simulation was done in the cylindrical coordinate system, using the test-particle Monte Carlo method and considering the real and three-dimensional geometry of the blade. Then the present work is validated and compared with experimental results and previous works. In the following, to investigate the effect of the blade angle in the middle and final stages of the turbomolecular pump, considering that three angles of 20, 15 and 10 degrees are mainly used in these stages, four different combinations of the aforementioned angles are presented for a five-stage turbomolecular pump. The four presented combinations have been evaluated based on the two parameters of maximum compression ratio and maximum flow rate at different blade speeds. Finally, it can be seen that different angles should be used for the middle and final stages of the turbomolecular pump, emphasizing the 15 degree angle compared to the 20 and 10 degree angles. It is also recommended to use an angle less than 10 degrees in order to achieve the maximum compression ratio and maximum flow rate.
Keywords
Turbomolecular Pump
Numerical Simulation
Test-Particle Monte Carlo Method
Returning Molecule
Blade Angle
Subjects
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  • Receive Date 28 July 2023
  • Revise Date 11 September 2023
  • Accept Date 25 September 2023
  • First Publish Date 25 September 2023
  • Publish Date 22 June 2023