Study On Leakage Characteristics Of Oil-gas Mixed Media In Scroll Compressor

Scroll compressor is a new type of fluid machinery,compared with other types of compressors,has the advantages of simple structure,stable performance,small flow fluctuation,high efficiency,small volume,light weight and so on.At present,it has been widely used in power,refrigeration,medicine and other fields.Because of the specific movement mode,machining accuracy and other problems,the compressor has the problem of leakage,there are difficulties in the compressor leakage control.At the same time,the existence of lubricating oil in the lubrication system not only meets the needs of lubrication and cooling of the compressor,but also plays a role of shock absorption and buffering,wear reduction,sealing and leakage prevention,rust prevention and corrosion prevention.The content of lubricating oil also has a great influence on the leakage of scroll compressor.Therefore,only in-depth study of leakage mechanism under different working conditions,reduce leakage,can further improve the efficiency of the compressor,reduce production costs,improve the performance of the compressor.In this paper,the leakage characteristics and flow field distribution of scroll compressor under different oil/gas volume ratio and different leakage clearance are studied by theoretical calculation method and numerical simulation method.First,considering the physical property of oil and gas mixed medium parameters on the leakage and the effect of the flow field distribution,on the basis of fluid mechanics,engineering thermodynamics,two phase fluid mechanics theory,by using the homogeneous model,within the compressor clearance leakage in system on the physical parameters of oil and gas mixed medium was calculated,and analyzed the two-phase flow area of the relationship between the parameters.The density,viscosity,adiabatic index of mixed media and the pressure in each compression chamber were calculated under different oil/gas volume ratios,which provided certain theoretical support for subsequent calculation of leakage.Then,according to the leakage characteristics of the meshing clearance of scroll compressor,the radial leakage model of the axial clearance and the tangential leakage model of the radial clearance are established,and the calculation formula of the corresponding leakage is derived.The clearance leakage under different oil/gas volume ratio is calculated by using MATLAB software.Finally,based on the basic geometric parameters of the scroll compressor,a three-dimensional watershed model of the compressor chamber was established and the mesh was divided.By using numerical simulation method,the flow field distribution and leakage law in the compression cavity with different oil/gas volume ratio and different radial clearance were obtained.The theoretical calculation results were compared with the numerical simulation results,and the feasibility of the model was verified.The results show that the leakage of scroll compressor is not only related to the size of leakage meshing clearance and pressure difference between compression chambers,but also the physical parameters of oil and gas mixture formed by lubricating oil and air have a certain influence on the leakage of the compressor.In a certain range,and meet the processing requirements,the smaller the meshing clearance,the lower the leakage.The more lubricating oil content,the less clearance leakage.When the oil/gas volume ratio is 2%,the clearance leakage is minimum.Therefore,reasonable control of volume ratio of oil and gas mixture and meshing gap in scroll compressor can effectively reduce the leakage of the compressor and improve the volume efficiency of the compressor.