过热液体中蒸汽泡上升过程的格子Boltzmann三维数值模拟

Three-dimensional Numerical Simulation of Vapor Bubble Rising in Superheated Liquid by Lattice Boltzmann Method

应用格子Boltzmann相变模型,在三维空间研究蒸汽泡在过热液体中生长、上升和变形等动力学行为.为研究传热传质对蒸汽泡运动的影响,对比模拟相同条件下气泡在等温环境中上升的物理过程.结果表明:蒸汽泡在过热液体中上升发生的变形程度较小,意味着相变对蒸汽泡的影响和表面张力一样使汽泡保持初始的形状.蒸汽泡在过热液体中的上升速度较小,说明随着汽泡生长拖拽力的影响比浮力大.蒸汽泡生长率在初始阶段达到最大值,随后会趋于一个恒定的值.随着汽泡体积增大和上升速度的增加,其对流场的扰动也越来越剧烈.蒸汽泡生长和上升引起的对流运动对温度场的演化造成很大的影响.

Dynamics behavior of a vapor bubble such as rising,growth and deformation in superheated liquid was simulated with three-dimensional lattice Boltzmann phase-change model.To study effect of heat and mass transfer on vapor bubble,process of bubble rising in isothermal system was simulated.It shows that deformation extent of vapor bubble is small in superheated liquid.It is suggested that the effect of phase-change on vapor bubble is similar to surface tension force,which makes vapor bubble tend to keep its initial shape.Rising velocity of vapor bubble in superheated liquid was smaller.It implied that the effect of drag force on vapor bubble was dominant in superheated situation.In addition,growth rate of vapor bubble reaches the maximum at initial stage;Then it tended to nearly a constant.As vapor bubble volume and velocity increase,influence of disturbance on flow field is more and more intense.Meanwhile,growth of vapor bubble and convection induced by bubble rising have great impact on evolution of temperature field.