Experimental Test And Performance Research On Different Rotor Stages Of Multistage Vacuum Dry Pump

The multi-stage vacuum dry pump has the advantages of high cleanliness and high integration.It can be combined with different rotors according to different pumping performance requirements.It is widely used in the chemical industry,film industry and semiconductor industry,and the market demand is growing.In order to meet the needs of different projects,vacuum pump manufacturers and experts at home and abroad have carried out many pumping principles and optimization upgrades for multi-stage vacuum dry pumps.Some foreign vacuum dry pump manufacturers started research on multi-stage vacuum dry pumps early.Its products occupy a very large share in China’s multi-stage vacuum dry pump market.China urgently needs to improve its independent research and development capabilities.This topic studies the performance of different rotor stages of multi-stage vacuum dry pumps from the aspects of simulation analysis and experimental test,and realizes the performance test methods of different rotors in different pressure sections,which gives guidance for the design of multi-stage vacuum dry pumps.In this paper,the Fluent software is used to simulate and compare the pumping performance of the Roots rotor with the two influencing factors of blade shape and clearance.The flow field in the cavity of the rotor rotating once pump is obtained by taking 1000Pa(higher vacuum side)and 101325pa(lower vacuum side)as the exhaust pressure and compression ratio of 3.3.In terms of blade shape,four rotor models were selected for comparison,with different numbers of leaves and shape coefficients respectively.The exhaust performance of different rotors was discussed in terms of higher vacuum side gas environment and low vacuum side gas environment.Selection of rotor blades for different pressure sections.In terms of clearance,three clearance models are selected to compare the two blade roots rotor and three blade roots rotor with the same shape coefficient.The higher vacuum side and the lower vacuum side are also selected under the same working condition.The influence degree of clearance under the two working conditions and the influence of clearance on the two model rotors are discussed.Combined with the processing of multi-stage vacuum dry pumps in practical engineering applications and the rotors at various levels,some references and suggestions are given for the gap selection of different rotor stages and the basis for rotor selection.This paper introduces the structure principle and manufacturing of the adjustable rotor test pump.Through the SolidWorks 3D software,the geometric modeling is carried out.In the process of communicating and following up the machining process of the cavity and rotor and other key parts,the structure of the adjustable rotor test pump is gradually improved and optimized.According to the assembly needs,the design of the tooling is carried out,the purchase of standard parts is completed,before assembly,leak detection of the cavity and dynamic balancing of the rotor were carried out.After assembly of the adjustable pump was achieved,the whole machine was leak tested.After adjusting the clearance between rotors according to the theoretical design data,the expansion sleeve is used to tighten the rotors,so that the adjustable pump rotors can be adjusted,and the performance test methods for different pressure sections of different rotors are studied.Taking the blade shape and clearance as variables,the air extraction performance test comparison is carried out in different pressure sections.When testing and comparing the performance of different blade shapes,in addition to the exhaust pressure of 1000Pa and 101325pa,the experimental control group with the exhaust pressure of 10000pa is added.According to the actual air extraction performance of the two blade roots rotor and the three blade roots rotor under different exhaust pressure conditions,the actual air extraction performance of the two rotors is tested The capability is compared,and its advantage condition is analyzed.At lower pressures,the two-lobe roots rotor can obtain higher ultimate vacuum.On the low-vacuum side,the three-lobe roots rotor exhibits better pumping performance.The experimental results are compared with the simulation results,the causes of the errors are analyzed,and the directions for further improvement are given.In the comparison experiments of different gap performances,considering the foregoing experimental effects,the exhaust pressures of 1000Pa and 10000Pa were selected as control groups for experimental research.The pumping speed and power consumption of different rotors under the two pressure sections were also recorded and compared.