The Study Of Slug Flow Model On Gas-liquid Two-phase Flow In Large Inclination Upward Pipe

Large inclination upward pipe is common in hilly terrain area.Due to the topography,slug flow is prone to produce in the gas-liquid two-phase flow in large inclination upward pipe.Slug flow has a negative effect on the production process.So far,the research on gas-liquid twophase flow of the in large inclination upward pipe are not very much.In order to study the flow characteristics,slug flow characteristics and model of slug flow in the gas-liquid mixing pipeline in large inclination upward pipe.A series of experiments and theoretical studies have been carried out.Obtained flow patterns and measured gas-liquid two-phase flow pressure fluctuations in the upward pipe using an indoor experiment apparatus.Six flow patterns were observed during the experiment.Obtained both time domain,PDF(Probability Distribution Function),CDF(Cumulative Distribution Function)and PSD(Power Spectral Density)characteristic values of the pressure fluctuation under different superficial gas velocity,superficial liquid velocity and angle.Analysis results show that: Due to the expansion of the gas and the inertia of the slug in the large inclination,the pressure value of the pressure sensing point would be lower than the higher point during the blowout of severe slugging;Compared and analyzed the characteristics of time domain,PDF,CDF and PSD characteristic values of the pressure fluctuation under different superficial gas velocity,superficial liquid velocity and angle,which can be used to identify flow patterns and provide reference for selection of equipment and the security operation of pipelines;Distributions of PDF show single-peak and dual-peak;The slope,knee,and distribution of CDF is different for different flow patterns;Distributions of PSD show single-peak,dual-peak,triple-peak,multi-peak and no–peak;The period and the value of pressure fluctuation of severe slugging increase with the angle augmented.The characteristic parameters of slug flow were analyzed according to experiments data under different diameter,different angle.The change rule of the characteristic parameters is obtained by analyzing the velocity of slug,slug length,slug distribution,slug frequency and liquid holdup of different angle,different pipe diameter,different gas velocity and different liquid velocity.A combined model is proposed to model the slug initiation,capture the development of slug and calculate hydraulic parameters in large inclination upward pipe.The model includes flow pattern judgment,slug capture and hydraulic parameter calculation.The flow pattern is based on empirical correlation,and the following flow patterns can be detected: separated bubble flow,stratified flow,ring mist flow,bubble flow,intermittent flow,and churn flow.Slip velocity equation and liquid mass conservation equation are the basement of the model.Build up a moving reference frame to solve the liquid mass conservation equation.Model slug initiation and development through the change of holdup.Combined with momentum equation and the influence of hilly terrain to calculate hydraulic parameters.Experimental date and field data(Daqing)were used to verify the model.Calculated results were compared with the calculated results from OLGA and Ledaflow.Analysis results show that: The accuracy of this model is fine.