Research On The Flow Pattern Threshold And Lubrication Characteristics Of Two-phase Flow Of The Oil-air Lubrication

The theory and application researches on the oil-air lubrication are paid more and more attention by researchers and engineers as it is widely applied in manufacturing industries.The flow pattern threshold of annular flow is obtained by simulation and experiment,lubrication characteristics of annular flow are researched by experiments,and the characteristics of disturbance wave from the oil film of annular flow are analyzed by simulation in this thesis,according to the actual working condition of oil-air lubrication system.The main research work and conclusions are shown as follows,The threshold of the annular flow is simulated.The dimensionless criterions from stratified flow to annular flow and from slug flow to annular flow are obtained employed the dimensional analysis method,and then pressure drop diagram about the two-phase flow is made,basing on above criterions,to recognize flow patterns.The results show that the two criterions are reasonable,and the pressure drop diagram is also consistent with the flow mechanism of the two-phase flow.The cross-section void fraction values changed with the time are collected by the ECT(Electrical Capacitance Tomography)under different interfacial speeds of air and oil,the FFT(Fast Fourier Transform)curve and the PDF(Probability Density Function)curve of the void fraction under different system condition are made,the recognition method of two-phase flow pattern of oil-air lubrication system is studied in detail.The results show that the experiment results and simulation results for all selected interfacial speed points are supported each other.The lubrication characteristics of the annular flow are analyzed employed the response surface methodology.The results show that the influence of annular flow forming under different air pressure and oil content on the different lubrication indexes of bush is different,and the interaction between the air pressure and the oil content is significant in the process of bush lubrication.The optimizing parameters of the lubrication system is obtained in this experiment.The disturbance wave characteristics of the annular flow are simulated,and the effect of the interfacial speed of air and oil on the disturbance wave characteristics is analyzed in detail.The results show that the periodicity of disturbance wave is getting worse with the increasing of interfacial speed of air phase when the interfacial speed of oil phase is constant,on the contrary,the similarity of disturbance wave pattern is getting worse.The influence of the air-oil interfacial speed on the power distribution of disturbance wave in low frequency and high frequency band is different.