液体介质对上升气泡几何形态和运动特征的影响

Effects of liquid medium on geometric and kinetic characteristics ofa rising bubble

利用高速摄像技术观测了不同液体介质(去离子水、离子水、5#白油和水-白油溶液)中气泡的上升行为。采用了三种不同直径的注气喷嘴。对比分析了气泡在不同工况条件下的上升速度、当量直径、纵横比和曳力系数。结果表明,气泡在不同的单一介质中的上升轨迹及运动特征不同,介质的黏度和表面张力均对气泡的形状和尺寸有着重要影响。此外,观测并分析了气泡穿过水-白油界面的行为,发现当气泡离开界面较远时,其运动形态与在单一介质中相似;气泡穿过界面时被液膜包覆,然后液膜自气泡表面脱离。小尺寸气泡在单一油中和穿过水-白油界面后的几何形态和运动特征相似,而大尺寸气泡在穿过水-白油界面后呈现曲折的运动轨迹,其纵横比发生明显变化。

The rising behavior of bubbles in different liquid media(deionized water,ionized water,5#white oil and water-white oil solution)was observed by using high-speed photography.Three air-injection nozzles with different outlet diameters were employed.A comprehensive comparison of the rising velocity,equivalent diameter,aspect ratio,and drag coefficient of bubbles obtained under different operating conditions was implemented.The results demonstrated that the trajectory and kinetic characteristics of the bubble varied considerably in different single mediums.The viscosity and surface tension of the medium exerted a significant effect on shape and size of the bubble.Additionally,behavior of the bubble passing through the water-white oil interface was investigated.It was observed that when the bubble was away from the interface,its motion resembled that observed in corresponding single medium.However,when the bubble crossed the interface,it was enveloped by a liquid film,which subsequently detached from the bubble.After passing through the water-white oil interface,small-sized bubbles exhibited the geometric and kinetic characteristics similar to those in single white oil.In contrast,large-sized bubbles were characterized by a zigzag trajectory after passing through the water-white oil interface.Meanwhile,the Journal,2023,74(10):4140-4152 bubble aspect ratio varied considerably.