Thermal Deformation Simulation of Scroll Elements in Oil-Free Scroll Vacuum Pump

The paper considers oil-free scroll vacuum pumps which are widely used in the nanomaterials industry, microelectronics, medicine, pharmaceuticals industry, and thermonuclear power engineering. Pumping characteristics of a scroll pump as well as any other non-contact machine depend largely on the backward gas leakage between the working chambers. The leakage is primarily determined by the values of radial and face clearances between the moving and fixed elements. The paper discusses thermal deformations of the moving and fixed scroll elements made of aluminum alloy illustrated by the example of an oil-free scroll vacuum pump with the geometrical pumping speed of 15 m³/h. The initial data used for thermal deformation calculation are believed to present the values of pressures and temperatures in each chamber of the scroll vacuum pump. They were obtained by both applying the mathematical model of the working process and observing the temperature pattern of all surfaces of the working elements. The Ansys package was used to perform the computation. It is shown that thermal deformations of the scroll elements are 5 to 7 times as much as force deformations. They are the key factor for determining clearances values in the scroll vacuum pumps. When a radial clearance is 0.1 mm, it can be changed up to 25 % due to thermal deformations.

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