Numerical Simulation Study On The Flow And Heat Transfer Characteristics Of The Bubble Rising Process

Bubble motion widely exists in various engineering practice,such as metallurgy,chemical industry and so on.In the process of bubble movement,the changes of kinetic energy and thermal parameters of the bubble itself,as well as the disturbance and heat transfer process of the bubble to surrounding liquid play a crucial role in the actual industrial operation results.With the rapid development of the field of multiphase flow,many problems of bubble movement have been solved,but the complexity,variability and unpredictability of bubble shape and temperature have brought great difficulties to the research of bubble movement,and it is difficult to obtain reliable and comprehensive data information under actual working conditions.The flow and heat transfer process of bubbles were studied and analyzed by numerical simulation method,and the real-time monitoring of the flow state and heat transfer effect of bubbles was realized.A single bubble flow heat transfer model was established.Taking the initial diameter as a variable,the flow characteristics and heat transfer effect of a single bubble with initial diameter of 0.02 m,0.025 m,0.03 m,0.035 m and liquid viscosity of 0.01pa·s were analyzed and studied.Taking liquid viscosity as a variable,the flow characteristics and heat transfer effect of single bubbles with initial diameter of 0.025 m and liquid viscosity of 0.01pa·s,0.2pa·s,0.4pa·s and 0.6pa·s were analyzed,and the conclusion was drawn: larger liquid viscosity can effectively improve the flow intensity of bubbles and reduce the heat transfer effect of bubbles.Order process of bubble rising in non-isothermal condition,the establishment of a single bubble motion flow heat transfer coupling model,studies the initial temperature of 375 k,350 k,335 k,320 k,bubble velocity and equivalent diameter of the viscosity and surface tension coefficient and air bubble,bubble interface Re,Eo and Mo,the change rule of the research results show that the bubble Re number is the most largest respectively 36974,25323,24662,24139;The Eo number decreased by 35.3%,25.2%,16.9% and 9.2% respectively.Mo accuracy rose 11.7 percent,8.4 percent,7.2 percent,and 5.0 percent.The higher the initial temperature of the bubble,the easier the transition to ellipsoid and spherical shape.For monitoring temperature of air bubbles in the process of bubble motion is difficult,for the isothermal heat transfer process in the bubble volume,the initial height,initial temperature,instantaneous height and the changing rule of the instantaneous temperature to the simulation result analysis of bubble volume,the initial height,initial temperature,instantaneous height fitting,the relationship between the instantaneous temperature,The results show that the error of calculation and simulation is less than 1.5%.The fitting formula has high accuracy and reliability.In order to explore the movement characteristics and heat transfer law of continuous bubbles in liquid,the numerical simulation of continuous bubble rising process was carried out to study the influence of liquid plume on bubble flow and heat transfer effect,as well as the influence of bubble diameter and surface tension coefficient on bubble flow and heat transfer effect in the plume environment.The results show that the liquid plume can effectively improve the flow intensity and heat transfer efficiency of the bubbles.In plume environment,larger bubble diameter can effectively improve bubble flow and heat transfer characteristics,and larger surface tension coefficient can effectively reduce bubble flow and heat transfer characteristics.