Characterization And Experimental Study Of The Rising Motion Characteristics Of Bubbles In A Vertical Tub

In gas-liquid two-phase flow,the motion of bubbles within the fluid can significantly affect the flow properties and processes.The study of bubble motion characteristics has always been one of the important directions in the study of gas-liquid two-phase flow,and although it has been explored by many researchers in the past decades,the study of bubble detachment and motion characteristics still has certain limitations.Based on the problems in the study,this paper uses high-speed camera technology and image processing techniques to investigate the laws that affect the bubble detachment and motion characteristics by factors such as the nature of the continuous phase,nozzle inner diameter,gas flow rate and continuous phase liquid level height.By combining experiment with theory,the motion characteristics of bubbles in gas-liquid two-phase flow are explored,which provides basic data for bubble behavior in industrial process.Firstly,the experimental platform for bubble detachment and motion was built,and the experimental platform was divided by function into two parts:the test system and the image acquisition system,and the specific components of each part of the experimental platform were introduced.The process of using Mathematical analysis software to process the bubble image was described in detail,and the processed bubble image was identified and extracted by mathematical analysis software recognition algorithm.The uncertainty of experiment and image processing was analyzed to ensure that the error of experimental study is within the acceptable range.Secondly,the formation and detachment characteristics of initial bubbles in stationary liquids at different experimental conditions were examined.A model for predicting the detachment diameter of bubbles in water and heat transfer oil was established,the model was also corrected by introducing a coefficient9),and the maximum error in the predicted value of the revised model is 14.36%.The results showed that the detachment diameter of bubbles in heat transfer oil is larger than that in water,and that the bubble shape in heat transfer oil is closer to a sphere than the ellipsoidal shape of the bubbles in water.With the increase of nozzle inner diameter and gas flow,the bubble diameter gradually increases,and the detachment shape gradually changes from spherical to ellipsoidal.With the increase in the height of the continuous phase of liquid,the bubble detachment diameter gradually decreases,the detachment shape change is not obvious.Finally,the motion characteristics of bubbles rising in stationary liquids at different Na Cl solution concentrations and gas flow rates were investigated,and a new index,bubble offset,was proposed to evaluate the degree of solution disturbance.Through the least square method fitting,the functional relationship(correlation coefficient R~2≥95%)of bubble diameter and velocity with the rise height was obtained,which accords with the power law distribution.The results show that the bubble motion is positively correlated with gas flow and negatively correlated with solution concentration.The degree of disturbance of the solution has an important effect on the bubble trajectory,the rate of rise and the coalescence.The bubble offset varies periodically with the rising height,and its functional relation is obtained.