Internal Flow Field Transient Simulation And Experimental Investigation For New Oil-free Scroll Compressor

As a new generation of positive displacement compressor,oil-free scroll compressors are widely used in industrial field due to their small components,high compression efficiency and small size.But in some special industri es,there are certain requirements for gas cleanliness,such as,medical equipment and food manufacturing.Today,scroll compressors are mostly oil lubricated,obviously,which does not meet the requirements of special industries for clean air.Based on th e research of the existing oil-free scroll compressor,a new type of oil-free scroll compressor prototype was developed in combination with the characteristics of compressor operation.For this type of prototype,the mathematical model is established on the basis of the original research,and then the C FD transient simulation calculation is carried out on the internal three-dimensional flow field and verified by experiments.The main research content includes the following points:(1)The theoretical knowledge of the oil-free scroll compressor profile is expounded,get the basic relationship of the profiles and the basic equation of the profile is obtained by theoretical calculation.Brief int roduction to the correction of the scroll tooth head and correct the tooth head of the compressor by using the dou ble arc and straight line correction method.The volum e of each working chamber is calculated and the variation of the volume with the rotatio n angle of the main shaft is obtained.(2)According to the geometric model of oil-free scroll compressor and its working characteristics,its mathematical model is est ablished and make a detailed analysis of its internal heat transfer and leakage.Accordi ng to the mass,momentum and energy conservation equations,the governing e quations of the working gas in the simulation calculation are established.Then,detailed ana lysis of its calculation method.The corresponding formula is given for the calculation of the oil-free scroll compressor power and the power is calculated under e ach working condition.(3)Establishing a three-dimensional flow field model for oil-free scroll compressor.The dynamic mesh technique is used to perform unsteady transient simulation calculations on the flow field with air as the working fluid.The three-dimensional distribution of temperature,pressure and velocity in the flow field of working gas under different working conditions is obtained by simulation.The variation law of the mass flow of the inlet and outlet with the rotation of the main shaft under different working conditions is obt ained and the corresponding leakage characteristics are obtained by comparing the difference.The law of the pressure of the working gas changes with the rotation angle of the main shaft.The influence of assembly clearance on the pressure change of workin g gas is obtained by simulating the flow field of oil-free scroll compressor with different assembly clearances.(4)Building a test platform to measure the performance parameters of oil-free scroll compressors under different working conditions.The true variation of the exhaust volume,exhaust temperature,power and the internal pressure of the working gas in the woking chamber is obtained.By comparing with the simulation results,not only the correctness and accuracy of simulation calculation are verifi ed,but also the necessary data support for the performance optimization of the model is provided.