Using the inertial coordinate system to investigate the effect of single-stage turbomolecular pump blade geometry on hydrogen gas discharge

The use of turbomolecular pumps (TMP) is necessary to create and maintain high-vacuum environments in various applications. Their pumping performance depends on the molecular weight of the pumped gas, with better efficiency observed in heavier gases compared to lighter gases. The pump's performance was studied for 12, 24, 36, and 48 blades in a single-stage turbomolecular pump at angles of 22°, 30°, 40°, and 45°, and blade thicknesses of 1.55 and 3.1 mm, with a clearance of 0.0166 (0.3 mm) for light gas (hydrogen). We also studied clearances of 0.000 556 (0.01 mm), 0.0166, and 0.027 778 (0.5 mm) for a blade number of 36 and a blade angle of 30°. The test particle Monte Carlo (TPMC) method in an inertial frame is used for this investigation. To validate the solution method, molecular flow passing through one stage of the turbomolecular pump is simulated, and the calculated results align well with available reference data, confirming the model's accuracy. Increasing the number of blades improves the compression ratio but reduces pumping speed. Smaller blade angles, such as 22°, enhance compression efficiency, while larger angles, such as 45°, improve pumping speed. Reducing blade thickness (from 3.1 to 1.55 mm) significantly increases pumping speed but has a lesser impact on the compression ratio. Clearance size has a minimal effect on performance within the range of 0.000 556–0.027 778, with the optimal value being 0.0166. This research provides valuable insights into how specific geometric adjustments affect turbomolecular pump performance and offers a practical tool for designers to optimize pump configurations for handling light gases such as hydrogen.