Method of Determining the Transition Boundary of Slug Flow to Churn Flow in Vertical Tubes

Experimental studies on determining the transition boundary of slug flow to churn flow are pressure and friction loss,the turning point of inside pressure curve is just the point where the churn flow takes place.According to the experimental data,the transition boundaries of slug flow to churn flow in two carried out in two tubes,which inside diameters are 15mm and 25mm,respectively.The results show that during the transition,the inside pressure experiences the changeable process from decrease to increase with the increase of the air flow rate.Based on the visual observation and the theoretical analysis of the inside different tubes are given.