Influence of inner reflux groove structure on flow characteristics of Roots pump
The Roots pump exhibits distinct features such as high gas pressure at the exhaust port,low pressure in the basic volume,and significant airflow pulsation at the outlet due to gas reflux.The entire flow field of an MB7300 Roots pump was numerically calculating by using the Pumplinx software.The Q criterion vortex identification method,coupled with Tecplot software,was employed for a qualitative analysis of the flow field of the Roots pump vortex structure.The primary aim was to investigate the im-pact of the internal reflux tank angle and thickness on the outlet pressure pulsation and internal pulsa-tions.The results indicate that the internal reflux tank structure has no significant effect on the inlet side flow pattern improvement.However,it can effectively diminish the exhaust pressure pulsation,flow pulsation,and vortex in the exhaust section.The study reveals that the effect is more pronounced with increased thickness.Nonetheless,excessive thickness and angle can result in a larger gap between the rotor and the housing,thereby exacerbating leakage and displacement reduction.The optimal angle and thickness of the internal reflux tank are determined to be 45°and 7.5 mm,respectively,which ef-fectively reduce pressure and flow pulsation while minimizing flow loss.To maintain a non-negative out-let flow rate,the internal reflux tank size can range from an angle of 45°to 60°and a thickness of 7.5 mm to 10.0 mm.The findings of this study can serve as a foundation for research on airflow pulsation and shell structure design optimization of Roots pumps.
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