A Probability Model Of Bubble Flow In Pipe

Bubble flow has good characteristics of mass and heat transfer,and is widely used in industrial practice.In bubble flow,the gas phase is mixed with the liquid phase in the form of bubbles.The gas-liquid two-phase structure of bubble flow is investigated by analyzing the motion and force states of bubbles.The most crucial bubble behaviors include the bubble collision and breakup,which continuously occur in the movement process of bubble flow.The bubble collision is usually brought by the drag force,buoyancy force,wall force and turbulence dispersion force.The coalescence efficiency of bubble collisions is analyzed to describe the bubble coalescence behavior.A novelty theory of bubble breakup is established according to the probability field analyses of the turbulent eddy.Then,the generation and elimination rates of an entire bubble group can be obtained by calculating the collision and breakup probabilities of a single bubble.Combing with the investigations on the random motion rules of a single bubble and an entire bubble group,a theoretical model is firstly established to predict the overall bubble size distribution based on the probability analyses of fully developed bubble flow.The predictions from the probability model agree well with the experimental data in terms of the bubble size distribution,and this demonstrates the availability of the theoretical model.Finally,the influences of different factors on the void fraction of bubbles and the coupling effects of various factors are investigated by calculating numerous designed conditions.