Fluid-Thermal-Solid Coupling Analysis And Performance Prediction Of Roots Vacuum Pump

Roots vacuum pump is widely utilized in industries such as petrochemical,electric power,semiconductor,food,light industry.With the increasing popularity of Roots vacuum pump in vacuum applications,modern engineering technology is increasingly performance requirements of Roots pump.At present,the research of Roots pump mainly focuses on rotor profile optimization design,calculation of internal leakage,airflow pulsation and gas flow characteristics in pump chamber.In this paper,the internal flow law and external characteristics of Roots vacuum pump were studied by means of theoretical analysis,numerical simulation and experimental verification.Then the influence of different parameters on the performance of Roots vacuum pump was systematically explored.The temperature and deformation of the Roots pump rotor system under pressure and temperature coupling were studied by the method of thermo-fluid-solid coupling,and the modal analysis of the rotor system of Roots pump was carried out.Finally,the external characteristic test was carried out on the Roots pump,and the numerical simulation results were verified with theoretical calculations and experimental tests.The specific work in this paper is as follows:(1)Theoretical calculations were carried out on the inlet flow,the pulsation of the flow,the temperature change during the flow and the temperature rise as well as shaft power of the Roots vacuum pump.Moreover,the research methods and related theories including thermofluid-solid coupling,Modal analysis were introduced.(2)Taking the Roots vacuum pump as the research object,the 3-D transient simulation of Roots pump was carried out by using 2.5D dynamic mesh technology,which included threedimensional SolidWorks modeling of Roots pump,ICEM meshing,numerical calculation and post-processing.Comparing and analyzing the flow law inside the air-cooled and ordinary Roots vacuum pump,the pressure changes in the working cycle,the pulsation of the airflow,the generation of vortex,the internal leakage and the backflow were investigated in detail.Moreover,the effects of parameters such as inlet pressure,rotor speed,rotor clearance,countercurrent cooling and intake air temperature on the performance of Roots pump were systematically studied.(3)The effects of temperature and pressure on deformation of the rotor were studied by the method of Thermo-Fluid-Solid coupling.The pressure and temperature of calculated by the fluid transient simulation were introduced to the surface of the rotor system,and the transient thermal calculation and static structure calculation of the air-cooled and ordinary Roots pump rotor system were carried out on the ANSYS Workbench collaborative simulation platform,respectively,so the effect of countercurrent cooling on rotor temperature,deformation and stress is studied.on this basis,the modal analysis of the Roots pump rotor system was carried out to obtain its natural frequency and mode shape to avoid resonance of the Roots pump rotor.(4)The effects of inlet pressure and speed on the volume efficiency and exhaust temperature of Roots pump were studied.The volume efficiency,exhaust temperature and efficiency obtained by the test were compared with the theoretical calculation and numerical simulation results.